U.S. patent number 5,649,536 [Application Number 08/391,701] was granted by the patent office on 1997-07-22 for blood pressure measuring apparatus.
This patent grant is currently assigned to Colin Corporation. Invention is credited to Toshihiko Ogura, Toru Oka.
United States Patent |
5,649,536 |
Ogura , et al. |
July 22, 1997 |
Blood pressure measuring apparatus
Abstract
A apparatus for measuring blood pressure of a living subject,
including a blood pressure measuring device which receives a
heartbeat synchronous-signal wave generated by arteries of the
patient, determines respective amplitudes of successive pulses of
said heartbeat-synchronous signal wave, each of which corresponds
to one heartbeat of the subject, and provides as a first series of
pulse amplitudes, the pulse amplitudes arranged in order of
generation. The device further smoothens the first series of pulses
and provides a second series of smoothened pulse amplitudes, and
determines a blood pressure value based on a change in the second
series. The device further provides a two-dimensional output of the
first and second series, where one of the two series is
superimposed on the other, and/or a representation of the degree of
propriety of the measurement condition during which the measurement
was performed.
Inventors: |
Ogura; Toshihiko (Inuyama,
JP), Oka; Toru (Ichinomiya, JP) |
Assignee: |
Colin Corporation (Komaki,
JP)
|
Family
ID: |
27549385 |
Appl.
No.: |
08/391,701 |
Filed: |
February 21, 1995 |
Foreign Application Priority Data
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Feb 25, 1994 [JP] |
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6-028164 |
Mar 1, 1994 [JP] |
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6-031064 |
Mar 1, 1994 [JP] |
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6-031567 |
Apr 5, 1994 [JP] |
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6-067112 |
May 17, 1994 [JP] |
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6-005342 U |
Sep 8, 1994 [JP] |
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6-214425 |
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Current U.S.
Class: |
600/493;
600/495 |
Current CPC
Class: |
A61B
5/02116 (20130101); A61B 5/022 (20130101); A61B
5/02225 (20130101); A61B 5/0225 (20130101); A61B
5/02208 (20130101) |
Current International
Class: |
A61B
5/0225 (20060101); G06F 17/00 (20060101); A61B
005/00 () |
Field of
Search: |
;128/672,670,680-683,687 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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60-241422 |
|
Nov 1985 |
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JP |
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61-103432 |
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May 1986 |
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JP |
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63-51837 |
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Mar 1988 |
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JP |
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2-25610 |
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Jun 1990 |
|
JP |
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5-137698 |
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Jun 1993 |
|
JP |
|
Primary Examiner: Nasser; Robert L.
Attorney, Agent or Firm: Oliff & Berridge
Claims
What is claimed is:
1. An apparatus for measuring a blood pressure of a living subject,
comprising:
an inflatable cuff adapted to be wound around a body portion of the
subject, said cuff being inflated to provide a cuff pressure to
press said body portion;
a pressure changing device which changes said cuff pressure;
a blood pressure measuring device which (a) obtains a
heartbeat-synchronous signal wave generated from arteries of said
body portion in synchronism with heartbeat of the subject while
said cuff pressure is changed by said pressure changing device, (b)
determines respective amplitudes of a plurality of successive
pulses of said heartbeat-synchronous signal wave each of which
corresponds to one cycle of heartbeat of the subject, and provides,
as a first series of determined pulse amplitudes, the determined
pulse amplitudes arranged in an order of generation of the
corresponding pulses, (c) smoothens said first series of determined
pulse amplitudes and thereby provides a second series of smoothened
pulse amplitudes, and (d) determines a blood pressure value of the
subject based on a change in said second series of smoothened pulse
amplitudes;
an output device which outputs a two-dimensional representation
comprising a number of picture elements; and
a control device which controls said output device to output said
two-dimensional representation representative of said first series
of determined pulse amplitudes and said second series of smoothened
pulse amplitudes such that one of said first and second series of
pulse amplitudes are superimposed on the other series of pulse
amplitudes.
2. An apparatus according to claim 1, wherein said output device
comprises means for outputting said two-dimensional representation
representative of said first and second series of pulse amplitudes
in a two-dimensional coordinate system defined by a first axis
indicative of cuff pressure and a second axis indicative of pulse
amplitude.
3. An apparatus according to claim 2, wherein said output device
further comprises means for outputting, along said first axis, at
least one symbol representative of said blood pressure value
determined by said blood pressure measuring device.
4. An apparatus according to claim 1, wherein said output device
comprises means for outputting said two-dimensional representation
comprising a first and a second representation selected from a
series of lines, a series of bars, and a polygonal line, said first
and second representations being representative of said first and
second series of pulse amplitudes, respectively.
5. An apparatus according to claim 1, wherein said output device
comprises means for outputting said two-dimensional representation
representative of said first series of determined pulse amplitudes
and said second series of smoothened pulse amplitudes such that
respective different portions of the determined pulse amplitudes
and the corresponding smoothened pulse amplitudes are indicated in
a color different from a color in which respective common portions
of the determined pulse amplitudes and the smoothened pulse
amplitudes are indicated.
6. An apparatus according to claim 1, wherein said output device
comprises at least one of an image display device and a
printer.
7. An apparatus for measuring a blood pressure of a living subject,
comprising:
an inflatable cuff adapted to be wound around a body portion of the
subject, said cuff being inflated to provide a cuff pressure to
press said body portion;
a pressure changing device which changes said cuff pressure;
a blood pressure measuring device which (a) obtains a
heartbeat-synchronous signal wave generated from arteries of said
body portion in synchronism with heartbeat of the subject while
said cuff pressure is changed by said pressure changing device, (b)
determines respective amplitudes of a plurality of successive
pulses of said heartbeat-synchronous signal wave each of which
corresponds to one cycle of heartbeat of the subject, and provides,
as a first series of determined pulse amplitudes, the determined
pulse amplitudes arranged in an order of generation of the
corresponding pulses, (c) smoothens said first series of determined
pulse amplitudes and thereby provides a second series of smoothened
pulse amplitudes, and (d) determines a blood pressure value of the
subject based on a change in said second series of smoothened pulse
amplitudes;
an output device which outputs a degree of propriety of a
measurement condition under which said blood pressure value of the
subject is determined by said blood pressure measuring device;
calculating means for calculating a degree of correction of said
second series of smoothened pulse amplitudes from said first series
of determined pulse amplitudes, by calculating a ratio of (a)
respective differences between (a1) the determined pulse amplitudes
corresponding to respective pressure values of said cuff within a
prescribed pressure range and (a2) the corresponding smoothened
pulse amplitudes, to (b) at least one of said determined pulse
amplitudes and said corresponding smoothened pulse amplitudes;
and
a control device which controls said output device to output said
degree of propriety of said measurement condition which corresponds
to the degree of correction of said second series of pulse
amplitudes calculated by said calculating means.
8. An apparatus according to claim 7, wherein said output device
comprises means for outputting a bar whose length is variable with
said degree of propriety of said measurement condition.
9. An apparatus according to claim 7, wherein said output device
comprises means for outputting one of a plurality of different
numbers corresponding to a plurality of degrees of propriety of
said measurement condition, respectively.
10. An apparatus according to claim 7, wherein said output device
comprises means for outputting one of a plurality of different
messages corresponding to a plurality of degrees of propriety of
said measurement condition, respectively.
11. An apparatus according to claim 7, wherein said output device
comprises outputting means for outputting a two-dimensional
representation comprising a number of picture elements
representative of said first series of determined pulse amplitudes
and said second series of smoothened pulse amplitudes such that one
of said first and second series of pulse amplitudes are
superimposed on the other series of pulse amplitudes.
12. An apparatus according to claim 11, wherein said outputting
means comprises a means for outputting said two-dimensional
representation with said degree of propriety of said measurement
condition.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the improvements of a blood
pressure measuring apparatus which measures a blood pressure value
of a living subject such as a patient.
2. Related Art Statement
There is known an automatic blood pressure (BP) measuring apparatus
which carries out BP measurements on a patient, accumulatively
stores a measured BP value or values obtained in each BP
measurement, and provides a graphic representation of the stored BP
values arranged in the order of measurement. An example of the BP
measuring apparatus is disclosed in Non-Examined Japanese Patent
Application laid open under Publication No. 5(1993)-137698. The BP
apparatus enables the patient to easily recognize the time change
of the measured BP values and correctly judge whether he or she is
in a healthy condition. When the patient feels tight in the chest,
such a light attack may, however, be transient, so that the patient
may fail to recognize that he or she possibly has a serious heart
disease. Even if the patient may reach the recognition and consult
a doctor, then the patient may no longer have any subjective
symptom and may appear to the doctor to have no medical problem. In
this case, the doctor may make a diagnosis based on insufficient
examination data, e.g., BP values only. If the prior BP apparatus
is used to obtain the BP values of the patient, however, the BP
apparatus provides only the measured BP values of the patient, or
only the time change of the measured BP values. With those data,
the patient may suspect that he or she may have hypertension, but
the patient cannot make a self-diagnosis, or the doctor cannot make
a medical diagnosis, that he or she may have a heart disease. If
the patient continues his or her life without receiving any medical
treatments, he or she might be brought into a serious
condition.
There is also known an automatic BP measuring apparatus which has a
BP measuring device for automatically measuring a BP value or
values of a living body, and a BP-value storing device for
accumulatively storing the BP values measured by the BP measuring
device from the living body. The BP measuring apparatus outputs the
BP values accumulatively stored in the BP-value storing device,
each time a new BP value or values of the subject is/are measured
by the BP measuring device. Thus, the living body can easily
recognize the time change of his or her BP values and effectively
utilize the BP values for his or her health control. However, in
the case where the BP values output from the BP apparatus do not
fall within a normal BP range and care should be taken of the
Living body, just the marshalling of figures would give only a weak
visual impression to the living body. Even if the living body may
recognize his or her blood pressure abnormality, he or she is
likely to forget it. While it is possible to output a pictorial
image together with the BP values to give a stronger visual
impression to the living body, it needs much time and effort to
prepare the pictorial image or images. Moreover, in the case where
a doctor gives a blood pressure-treating medicine to a patient
after having made a diagnosis based on measured BP values, it may
be somewhat cumbersome for the doctor to explain the directions for
use of the medicine, the objects of administration of the same, and
other necessary items.
Next, there is known an arm belt which is, either manually or using
a winding device, wound around an upper arm of a living body or
subject and which has an inflatable bag to which a pressurized air
is supplied to press the arteries of the arm and measure a BP value
or values of the subject. The supplying of the air to the bag is
effected after the belt is wound around subject's arm, and the
measurement of BP values is carried out while the air pressure of
the bag is changed. It is preferred that the belt be wound around
the arm such that three fingers can be inserted between the skin of
the arm and the inside surface of the belt. However, since the
upper arm of the subject around which the arm belt is wound is
easily deformable, a certain level of skill is needed for winding
the belt wound the arm with a preferable pressing force and
measuring a BP value or values of the subject with accuracy. Hence,
there has been used a winding device which automatically winds an
arm belt around an upper arm of a living subject. The automatic
winding device has a cylindrical arm receiver in which the belt
taking a cylindrical shape is provided, and has a drive device such
as a motor for tightening the belt. After the subject inserts his
or her arm into the belt inside the receiver through one end of the
receiver, the drive device is operated to tighten the belt and
thereby reduce the inside diameter of the cylindrical belt. Thus,
the arm belt is automatically wound around the subject's upper arm.
When a BP measurement is carried out using the automatic winding
device, it is required that the arteries of the upper arm of the
subject be uniformly pressed by the arm belt. To this end,
generally, an elbow rest is provided outside the other end of the
arm receiver, and the subject inserts his or her arm such that the
elbow of the arm rests on the rest. The diameter of the belt is
reduced when the subject is taking such a posture that the upper
arm is not in contact with the inner wall of the above-mentioned
one end of the receiver. That is, it is preferred that the
longitudinal axis line of the upper arm of the subject be kept
substantially parallel to the central axis line of the cylindrical
arm receiver. However, ordering the subject to change his or her
natural posture to the above-mentioned posture may result in
forcing the subject to take an unnatural posture, depending upon
the conformation of his or her body. This problem is exaggerated in
particular for patients or aged persons who are not so free to
change their postures. In the latter cases, the accuracy of BP
measurements may be lowered.
There is known a BP monitor apparatus which monitors the blood
pressure of a living subject. The BP monitor apparatus includes an
automatic BP measuring device including an inflatable cuff adapted
to be wound around a body portion of the subject. The automatic BP
measuring device is iteratively started to measure a BP value or
values of the subject. Thus, the BP monitor apparatus carries out
BP measurements periodically, i.e., at a prescribed measurement
period. However, if the measurement period is prescribed at so
short a period to improve the reliability of the BP monitoring, the
frequency of pressing of the subject's body portion with the cuff
is increased so that the subject feels a heavy burden. In this
situation, there has been proposed a BP monitor apparatus which
increases the pressure of an inflatable cuff wound around a body
portion of a living subject, up to a prescribed target pressure
value, detects a pulse wave as a pressure oscillation produced in
the cuff, and continuously estimates a BP value or values based on
a magnitude or magnitudes of each of successive
heartbeat-synchronous pulses of the pulse wave. Examples of this BP
monitor apparatus are disclosed in Non-Examined Japanese Patent
Applications No. 61(1986)-103432 and No. 60(1985)-241422. In the
latter case, however, if the target pressure is prescribed at as
low as possible a value to reduce the burden to the subject, it
might be difficult to detect the change of respective amplitudes of
successive pulses of the pulse wave corresponding to the change of
BP values of the subject. That is, the reliability of the BP
monitoring is lowered. The pulse amplitudes detected from the cuff
set on people having normal blood pressure change with the cuff
pressure so as to have an envelope indicated at solid line in FIG.
29, whereas the pulse amplitudes obtained from people having low
blood pressure change with the cuff pressure so as to have an
envelope indicated at broken line. Since the amount of change of
the pulse amplitudes with respect to the amount of change of the BP
values of a subject is more or less small where the pulse
amplitudes are obtained at a relatively low cuff pressure such as a
value, P.sub.K, shown in FIG. 29, the reliability of the BP
monitoring at the low cuff pressure P.sub.K is insufficiently
low.
Furthermore, there is known an automatic BP measuring apparatus
which quickly increases the pressure of an inflatable cuff wound
around a body portion of a living subject, up to a target pressure
value at which the inflated cuff stops the blood flow through the
arteries of the body portion, subsequently slowly decreases the
cuff pressure at a rate of 2 to 3 mmHg/sec, and measures a BP value
or values of the subject during the slow decreasing of the cuff
pressure. There are known two BP measuring techniques, i.e.,
oscillometric method and Korotkoff-sound method. In the
oscillometric method, the pressure oscillation produced in the cuff
during the slow decreasing of the cuff pressure is detected as a
pulse wave, and the systolic and diastolic BP values of the subject
are determined based on the change of respective amplitudes of
successive heartbeat-synchronous pulses of the pulse wave. In the
Korotkoff-sound method, the Korotkoff sounds, i.e., blood-flow
sounds produced from the arteries of the body portion during the
slow decreasing of the cuff pressure are detected using a
microphone, and the systolic and diastolic BP values of the subject
are determined based on the two cuff-pressure values at which the
first and last Korotkoff sounds are detected, respectively. In
these BP measuring methods, the accuracy of measurement of BP
values depends on the amount of change of the cuff pressure
corresponding to the interval of occurrence of the successive
pulses of the pulse wave or the successive Korotkoff sounds.
Therefore, for measuring the BP value or values of the subject with
accuracy, the automatic BP measuring apparatus carries out the BP
measurement while the cuff pressure is slowly decreased. However,
since in the prior BP measuring apparatus the cuff pressure is
slowly decreased in carrying out the BP measurement, it takes about
twenty seconds to obtain the measured BP value or values of the
subject. Before this slow cuff-pressure decreasing, no BP value is
available to a medical worker such as a doctor. In the case where a
doctor should make a quick decision on an emergency patient, or in
the case where a target value higher by a prescribed value than the
systolic BP value of a subject should be determined while the cuff
pressure is quickly increased, so that the cuff pressure is stopped
at the thus determined target value, it is required that a BP value
of the subject be known, even though it is rough, before a BP
measurement is carried out during the slow decreasing of the cuff
pressure.
Moreover, there is known the oscillometric BP measuring method in
which heartbeat-synchronous signal waves generated from arteries of
a living subject are collected while the pressure of an inflatable
cuff applied to the arteries is changed, the respective amplitudes
of the signal waves are determined to provide a series of wave
amplitudes arranged in the order of generation of the signal waves,
and a BP value of the subject is determined based on a change of
the series of wave amplitudes according to a prescribed software
algorithm. An example of the BP measuring method is disclosed in
Examined Japanese Patent Application laid open for opposition under
Publication No. 2(1990)-25610 assigned to the Assignee of the
present U.S. application. The Japanese document discloses a BP
measuring apparatus which measures a BP value of a living subject
according to the oscillometric BP measuring method, i.e.,
prescribed software algorithm. The BP measuring apparatus has a
display device which displays a series of wave amplitudes in a
two-dimensional graph having a first axis indicative of the cuff
pressure and a second axis indicative of the wave amplitude. A
medical worker such as a doctor can easily recognize, from the
distribution of the wave amplitudes with respect to the cuff
pressure, the amounts of error of the BP measurement due to
external causes such as the physical motion of the subject and the
noise produced from peripheral devices. Thus, the doctor can judge
whether the conditions of the BP measurement are proper or
appropriate. A series of wave amplitudes displayed in the
two-dimensional area provided on the display device may define a
complex envelope changeable depending upon external factors. There
have been employed various smoothening techniques each of which is
used to smoothen the envelope of the wave amplitudes obtained in
carrying out a BP measurement. The BP measuring method disclosed in
Non-Examined Japanese Patent Application laid open for inspection
under Publication No. 63(1988)-51837 is one of the smoothening
techniques. In this method, an odd number of successive amplitudes
are selected from the series of amplitudes, and the amplitude
positioned at the center of the selected amplitudes is replaced
with the amplitude having the median magnitude. This is the
so-called medical filter. By sequentially repeating this
median-filter treatment with all the amplitudes by removing the
oldest one of the odd number of amplitudes and adding the following
amplitude, the envelope of the amplitudes is smoothened. Since a BP
measurement is carried out based on the thus smoothened envelope of
the amplitudes, the accuracy of measurement of BP values is
increased. Although a series of amplitudes are displayed as a
two-dimensional graph on the display device, the amplitudes defines
only a smoothened envelope wherein the errors of amplitudes due to
external factors have been corrected. From a smoothened envelope, a
doctor cannot judge whether the conditions of measurement of BP
values are proper, unlike a non-smoothened envelope showing the
distribution of non-treated "raw" amplitudes from which the doctor
can judge.
SUMMARY OF THE INVENTION
It is a first object of the present invention to provide a blood
pressure measuring apparatus which enables a patient or a doctor to
recognize the time change of the waveforms of pulse waves of the
patient and judge whether the patient has a heart disease, when a
BP value or values is/are measured on the patient.
The first object has been achieved by the present invention.
According to a first aspect of the present invention, there is
provided an apparatus for measuring a blood pressure of a living
subject, comprising: a blood pressure measuring device which
measures a blood pressure value of the subject; a first memory
which stores a plurality of blood pressure values measured by the
blood pressure measuring device, in an order of measurement of the
blood pressure values; a pulse wave detecting device which detects
a pulse wave produced from an arterial vessel of the subject in
synchronism with heartbeat of the subject while each of the blood
pressure values is measured by the blood pressure measuring device;
a second memory which stores a waveform of the pulse wave detected
by the pulse wave detecting device, in the order, the second memory
storing the respective waveforms of the pulse waves each of which
is detected by the pulse wave detecting device while a
corresponding one of the blood pressure values is measured by the
blood pressure measuring device; and an output device which outputs
the blood pressure values stored in the first memory, in the order,
and a plurality of curves respectively representing the waveforms
stored in the second memory, in the order, in a side-by-side
relation with each other.
In the BP measuring apparatus in accordance with the first aspect
of the invention, the output device outputs the BP values stored in
the first memory, in the order of measurement of those BP values,
and a plurality of curves representing the waveforms stored in the
second memory, in the same order, in a side-by-side relation with
each other. The output device may operate in this manner, when the
BP apparatus operates for measuring a BP value or values of a
living subject such as a patient. Since the BP apparatus is easily
used, the patient or a medical worker can easily recognize the time
change of the waveforms of the pulse waves of the patient together
with the time change of the BP values of the patient. Therefore,
the patient or the medical worker can make a diagnosis that the
patient may have a heart disease.
In a preferred embodiment in accordance with the first aspect of
the invention, the blood pressure measuring device comprises an
inflatable cuff adapted to be wound around a body portion of the
subject, and the pulse wave detecting device comprises a sensor
which detects, as the pulse wave, a pressure oscillation produced
in the cuff in synchronism with heartbeat of the subject. In this
embodiment, the sensor used as part of the blood pressure measuring
device is also used to detect the pulse wave of the patient. Since
an exclusive pulse-wave sensor is not needed, the BP apparatus
enjoys a simple construction and a low manufacturing cost.
In another embodiment in accordance with the first aspect of the
invention, the BP measuring apparatus further comprises amplitude
modifying means for modifying an amplitude of each of the waveforms
detected by the pulse wave detecting device, so that the waveforms
output by the output device have a prescribed amplitude. In this
embodiment, the patient or the doctor can easily compare the
waveforms of the pulse waves with each other, so that the patient
or the doctor can correctly recognize the time change of the
waveforms. In this case, the BP measuring apparatus may further
comprise wavelength modifying means for modifying a wavelength of
the each of the waveforms detected by the pulse wave detecting
device, so that the waveforms output by the output device have a
prescribed wavelength.
In yet another embodiment in accordance with the first aspect of
the invention, the BP measuring apparatus further comprises:
evaluating means for evaluating a characteristic of each of the
waveforms detected by the pulse wave detecting device, and
providing an evaluated value of the each waveform; and a third
memory which stores the evaluated value of the each waveform, in
the order, wherein the output device outputs the evaluated values
stored in the third memory, in the order. In this embodiment, the
patient or the doctor can quantitatively figure out the change of
the pulse waves, so that the patient or the doctor can more easily
recognize the time change of the waveforms of the pulse waves.
In another embodiment in accordance with the first aspect of the
invention, the output device comprises means for outputting a first
graphical representation indicating the blood pressure values
stored in the first memory, and a second graphical representation
indicating the evaluated values stored in the third memory, along a
common axis indicative of time, and outputting the curves
representing the waveforms stored in the second memory, along the
common axis. In this embodiment, the BP values, and the evaluated
values of the waveforms of the pulse waves are output together with
the curves of waveforms along a common "time" axis. The patient or
the doctor can more easily recognize the time change of the
waveforms.
It is a second object of the present invention to provide an
automatic blood pressure measuring apparatus which enables a living
body or subject to have a strong visual impression that he or she
has a blood pressure abnormality.
The second object has been achieved according to a second aspect of
the present invention, which provides an apparatus for measuring a
blood pressure of a living subject, comprising: a blood pressure
measuring device which measures a blood pressure value of the
subject; a first memory which accumulatively stores a plurality of
blood pressure values measured by the blood pressure measuring
device; a second memory which stores a plurality of pictorial
images each of which indicates a corresponding one of a plurality
of different evaluations of the blood pressure of the subject;
image selecting means for selecting one of the pictorial images
which corresponds to a current blood pressure value of the subject
measured by the blood pressure measuring device; and an output
device which outputs the one pictorial image selected by the image
selecting means, together with the blood pressure values stored in
the first memory.
In the BP measuring apparatus in accordance with the second aspect
of the invention, the output device outputs a pictorial image
selected by the image selecting means, together with the BP values
stored in the first memory. The pictorial image selected by the
image selecting means corresponds to a current BP value of the
subject measured by the blood pressure measuring device. Thus, the
subject can have a strong visual impression that his or her blood
pressure is abnormal, and can keep it in mind for a long time.
In a preferred embodiment in accordance with the second aspect of
the invention, the second memory stores a plurality of groups of
pictorial images each image of which indicates a corresponding one
of a plurality of different evaluations of the blood pressure of
the subject, and wherein the apparatus further comprises: a data
obtaining device which obtains identification data identifying the
subject; and group selecting means for selecting one of the groups
of pictorial images which corresponds to the identification data
obtained by the data obtaining device, so that the image selecting
means selects the one pictorial image from the selected group of
pictorial images. In this embodiment, the group selecting means may
be adapted to select a group of pictorial images based on the
identification data including the personal information of the
subject, such as sex, age, and clinical history. Thus, the image
selecting means selects a pictorial image which accurately
corresponds to a current BP value of the subject measured by the
blood pressure measuring device.
In another embodiment in accordance with the second aspect of the
invention, the output device comprises a printer which outputs, on
a recording sheet, the one pictorial image selected by the image
selecting means, together with the blood pressure values stored in
the first memory. In this embodiment, the subject can bring the
recording sheet on which the selected pictorial image is recorded.
Thus, the subject is not required to write down the measured BP
values or keep them in mind.
In yet another embodiment in accordance with the second aspect of
the invention, the output device comprises means for outputting a
graphic representation indicating a time change of the blood
pressure values stored in the first memory. In this embodiment, the
subject can easily recognize the time change of the BP values.
It is a third object of the present invention to provide an
automatic blood pressure measuring apparatus which is easily
operable for producing a pictorial image.
The third object has been achieved according to a third aspect of
the present invention, which provides an apparatus for measuring a
blood pressure of a living subject, comprising: a blood pressure
measuring device which measures a blood pressure value of the
subject; a first memory which accumulatively stores a plurality of
blood pressure values measured by the blood pressure measuring
device; a second memory which stores at least one pictorial image;
an output device which outputs the pictorial image stored in the
second memory, together with the blood pressure values stored in
the first memory; an image reading device which reads an original
image from an original; an editing device which is operable for
editing the original image read by the image reading device; and a
registering device which registers the image edited by the editing
device, by storing the edited image as the pictorial image in the
second memory.
In the BP measuring apparatus in accordance with the third aspect
of the invention, the image reading device reads an original image
from an original, the editing device is operable for editing the
original image, and the registering device registers the edited
image, by storing it in the second memory. The output device
outputs the edited image, i.e., pictorial image together with the
BP values stored in the first memory. The pictorial image
accompanying the BP values enable the subject to keep the BP values
in mind. In addition, the pictorial image is easily prepared and
registered in the present BP measuring apparatus.
In a preferred embodiment in accordance with the third aspect of
the invention, the second memory stores a plurality of pictorial
images each of which is related to a time of measurement of the
blood pressure of the subject, and wherein the apparatus further
comprises: a clock device which produces a signal indicative of a
time when the blood pressure measuring device measures a blood
pressure value of the subject; and image selecting means for
selecting one of the pictorial images which corresponds to a time
of measurement of a current blood pressure value of the subject
measured by the blood pressure measuring device, so that the output
device outputs the selected one pictorial image together with the
blood pressure values stored in the first memory. In this
embodiment, the second memory may be adapted to store pictorial
images each related to the date and time of measurement of a BP
value of the subject, for example, pictorial images representing
flowers at four seasons, landscapes at four seasons, etc. The
pictorial image accompanying the measured BP values gives a strong
visual impression to the subject, so that the subject can keep the
BP values in mind.
In another embodiment in accordance with the third aspect of the
invention, the second memory stores a plurality of random
selectable pictorial images, and wherein the apparatus further
comprises: a random value generator which provides, according to a
random function, a random value in response to an operation of the
blood pressure measuring device; and image selecting means for
selecting one of the pictorial images which corresponds to a random
value produced by the random value generator, so that the output
device outputs the selected one pictorial image together with the
blood pressure values stored in the first memory. In this
embodiment, in different BP measurements, different pictorial
images may be output together with the BP values of the subject.
The different pictorial images help the subject to keep the BP
values in mind.
It is a fourth object of the present invention to provide an
automatic blood pressure measuring apparatus which provides
information related to a medicine to be given to a patient, thereby
enabling a medical worker to omit the directions for use of the
medicine.
The fourth object has been achieved according to a fourth aspect of
the present invention, which provides an apparatus for measuring a
blood pressure of a living subject, comprising: a blood pressure
measuring device which measures a blood pressure value of the
subject; a first memory which accumulatively stores a plurality of
blood pressure values measured by the blood pressure measuring
device; a second memory which stores a plurality of batches of
medicine-related information each of which is related to a
corresponding one of a plurality of medicines administrable in
treating the blood pressure of the subject; an input device which
is operable for specifying one of the medicines; and an output
device which selects, from the second memory, one of the batches of
medicine-related information which corresponds to the one medicine
specified by the input device, and outputs the selected batch of
medicine-related information, together with the blood pressure
values stored in the first memory.
In the BP measuring apparatus in accordance with the fourth aspect
of the invention, the output device selects, from the second
memory, one of the batches of medicine-related information which
corresponds to the one medicine specified by the input device, and
outputs the selected batch of medicine-related information,
together with the blood pressure values stored in the first memory.
In the case where a doctor gives a BP-treating medicine to a
patient after having made a diagnosis based on the measured BP
values of the patient, the doctor is just required to specify the
medicine through the input device, so that the output device
outputs, together with the BP values of the patient, the batch of
information related to the medicine, the information including the
directions for use of the medicine, the objects of administration
of the same, and other necessary items. Thus, the doctor is not
required to provide any explanation to the patient.
It is a fifth object of the present invention to provide an
apparatus for automatically winding an arm belt around an upper arm
of a living subject, in measuring a blood pressure of the subject,
wherein the apparatus permits the subject to keep his or her
natural posture and ensures that the measurement of BP values is
carried out with accuracy.
The fifth object has been achieved according to a fifth aspect of
the present invention, which provides an apparatus for winding an
arm belt including an inflatable bag, around an upper arm of a
living subject, in measuring a blood pressure of the subject, a
pressurized air being supplied to the bag to inflate the bag and
thereby press the upper arm, the apparatus comprising: an arm
receiver inside which the arm belt is provided so as to define a
substantially cylindrical space into which the upper arm of the
subject is inserted from one of opposite ends of the cylindrical
space; a positioning device which changes a position of the arm
receiver relative to the upper arm of the subject; a detector which
detects a misalignment of a central axis line of the cylindrical
space of the arm receiver from a longitudinal axis line of the
upper arm of the subject; and a control device which controls,
based on the misalignment detected by the detector, the positioning
device to change the position of the arm receiver relative to the
upper arm so that the central axis line of the cylindrical space of
the arm receiver is substantially aligned with the longitudinal
axis line of the upper arm.
In the arm-belt winding apparatus in accordance with the fifth
aspect of the invention, when the subject inserts his or her upper
arm into the arm receiver, the detector detects the misalignment of
the central axis line of the arm receiver from the longitudinal
axis line of the upper arm of the subject, and the control device
controls, based on the misalignment detected by the detector, the
positioning device to change the position of the arm receiver
relative to the upper arm so that the central axis line of the arm
receiver is substantially aligned with the longitudinal axis line
of the upper arm. Thus, the present apparatus ensures that the
upper arm is suitably inserted such that the arteries of the upper
arm are not locally or partially pressed by the belt, without
requiring the subject to change his or her posture. That is, the
present apparatus ensures that the measurement of BP values is
effected with accuracy, permitting the subject to keep his or her
natural posture.
It is a sixth object of the present invention to provide a BP
monitoring apparatus which monitor the blood pressure of a living
subject with high reliability and without giving any burden on the
subject.
The sixth object has been achieved according to a sixth aspect of
the present invention, which provides an apparatus for monitoring a
blood pressure of a living subject, comprising: an inflatable cuff
adapted to be wound around a body portion of the subject, the cuff
being inflated to provide a pressure to press the body portion; a
detector which detects a plurality of pulse amplitudes produced in
the cuff being inflated to press the body portion; a pressure
changing device which increases the pressure of the cuff to a
prescribed value lower than a mean blood pressure of the subject,
and subsequently decreases the cuff pressure from the prescribed
value, in each of a plurality of periodic cycles; rate-of-change
determining means for determining, with respect to the cuff
pressure, a rate of change of the pulse amplitudes detected by the
detector while the cuff pressure is changed by the pressure
changing device; and first abnormality judging means for judging,
based on the determined rate of change, whether the blood pressure
of the subject is abnormal.
In the blood pressure monitoring apparatus in accordance with the
sixth aspect of the invention, the rate-of-change determining means
determines, with respect to the cuff pressure, a rate of change of
the pulse amplitudes detected by the detector while the cuff
pressure is changed by the pressure changing device, and the first
abnormality judging means judges, based on the determined rate of
change, whether the blood pressure of the subject is abnormal. The
BP monitoring of the present apparatus is carried out on the
discovery that the rate of change of a low-pressure-side portion of
the envelope of the pulse amplitudes with respect to the cuff
pressure changes as the blood pressure of the subject changes.
Therefore, the reliability of the BP monitoring is improved so
much. In addition, since the rate of change of the pulse amplitudes
is obtained while the cuff pressure is changed in a low-pressure
range between atmospheric pressure and the prescribed low pressure,
the subject is free of the burden.
In a preferred embodiment in accordance with the sixth aspect of
the invention, the monitoring apparatus further comprises a blood
pressure measuring device which automatically measures a blood
pressure value of the subject in a series of prescribed steps when
the first abnormality judging means judges that the blood pressure
of the subject is abnormal. In this embodiment, the BP value of the
subject just at the time of finding of the blood pressure
abnormality is obtained by the blood pressure measuring device. The
thus obtained BP value is clinically important, so that a medical
worker such as a doctor can make an appropriate treatment on the
subject such as a patient.
In another embodiment in accordance with the sixth aspect of the
invention, the first abnormality judging means comprises means for
judging whether a pulse amplitude detected by the detector while
the cuff pressure is changed by the pressure changing device, is
smaller than a reference value, the first abnormality judging means
judging that the blood pressure of the subject is abnormal, when
the pulse amplitude is smaller than the reference value. Since the
envelope of pulse amplitudes obtained from people suffering from
low blood pressure because of being in a shock state, is more or
less flat with respect to the cuff pressure, it is considerably
difficult to identify an abnormally low blood pressure based on the
rate of change of the pulse amplitudes with respect to the cuff
pressure. In this embodiment, however, since a pulse amplitude is
compared with a reference value to identify the blood pressure
abnormality, the reliability of identification of the subject's
shock state is improved.
In yet another embodiment in accordance with the sixth aspect of
the invention, the pressure changing device comprises means for
holding the cuff pressure at the prescribed value for a prescribed
period of time, and the apparatus further comprises second
abnormality judging means for judging, based on a pulse amplitude
detected by the detector during the prescribed period, whether the
blood pressure of the subject is abnormal. Since the two sorts of
abnormality judging means are employed in the present BP monitoring
apparatus, the reliability of the BP monitoring is much more
improved.
In another embodiment in accordance with the sixth aspect of the
invention, the pressure changing device comprises means for
increasing and holding the cuff pressure to and at a first
prescribed value, and subsequently increasing and holding the cuff
pressure to and at a second prescribed value higher than the first
prescribed value, and the rate-of-change determining means
comprises means for determining, with respect to the cuff pressure,
a rate of change of a pulse amplitude detected by the detector when
the cuff pressure is held at the second prescribed value from a
pulse amplitude detected by the detector when the cuff pressure is
held at the first prescribed value. In this embodiment, the
rate-of-change determining means determines, with accuracy, the
rate of change of a low-pressure-side increasing portion of the
envelope of the pulse amplitudes, based on the respective pulse
amplitudes detected at the first and second cuff-pressure values.
Thus, the reliability of the BP monitoring of the present apparatus
is improved. In this case, the rate-of-change determining means may
be adapted such that, if at least two successive pulses having
substantially the same pulse amplitude are detected while the cuff
pressure is held at each of the first and second values, the
determining means employs that pulse amplitude in determining the
rate of change of the pulse amplitudes. Since in this modified
manner "noise" pulses are removed from true pulses, the reliability
of the BP monitoring is still more improved.
In another embodiment in accordance with the sixth aspect of the
invention, the monitoring apparatus further comprises second
abnormality judging means for judging whether the blood pressure of
the subject is abnormal, based on a pulse amplitude detected by the
detector when the cuff pressure is held at the second prescribed
value. In this embodiment, it is not necessary to provide an
exclusive cuff-pressure holding period during which to detect a
pulse amplitude to be used by the second abnormality judging means
for judging whether the subject has blood pressure abnormality.
In another embodiment in accordance with the sixth aspect of the
invention, the monitoring apparatus further comprises a blood
pressure measuring device which automatically measures a blood
pressure value of the subject in a series of prescribed steps when
at least one of the first and second abnormality judging means
judges that the blood pressure of the subject is abnormal. In this
embodiment, when at least one of the first and second abnormality
judging means judges that the blood pressure of the subject is
abnormal, the blood pressure measuring device automatically
measures a blood pressure value of the subject. Thus, the
reliability of the BP monitoring is improved so much.
In another embodiment in accordance with the sixth aspect of the
invention, the first abnormality judging means comprises means for
judging whether the determined rate of change is greater than a
reference value, the first abnormality judging means judging that
the blood pressure of the subject is abnormal when the determined
rate of change is greater than the reference value, and the
apparatus further comprises: an input device which is operable for
inputting a desired value as the reference value; and changing
means for changing, based on the input value as the reference
value, the prescribed value to a new value to which the cuff
pressure is increased by the pressure changing device. In this
embodiment, the cuff pressure applied to the living subject such as
a patient is reduced to as low as possible a value.
It is a seventh object of the present invention to provide an
automatic blood pressure measuring apparatus which has the function
of estimating a BP value of a living subject before an actual BP
value of the subject is measured during the decreasing of the cuff
pressure.
The seventh object has been achieved by the present invention.
According to a seventh aspect of the invention, there is provided
an apparatus for automatically measuring a blood pressure of a
living subject, comprising: an inflatable cuff adapted to be wound
around a body portion of the subject, the cuff being inflated to
provide a cuff pressure to press the body portion; a pressure
sensor which detects the cuff pressure; a pressure changing device
which changes the cuff pressure; a blood pressure measuring device
which measures a blood pressure value of the subject by reading the
cuff pressure detected by the pressure sensor while the cuff
pressure is decreased at a prescribed rate by the pressure changing
device; a waveform detector which detects a waveform of a pulse
wave produced in the cuff during the decreasing of the cuff
pressure, the waveform of the pulse wave being changeable with the
cuff pressure; determining means for determining a relationship
between (A) evaluated values of a waveform of a pulse wave, (B)
pressure values of the cuff, and (C) blood pressure values of the
subject, based on (a) an evaluated value of the waveform of the
pulse wave detected by the waveform detector, (b) a pressure value
of the cuff at a time of detection of the waveform by the waveform
detector, and (c) the blood pressure value of the subject measured
by the blood pressure measuring device, the relationship being
proper to the subject; and estimating means for estimating,
according to the determined relationship, a blood pressure value of
the subject based on (a') an evaluated value of a waveform of a
pulse wave detected by the waveform detector while the cuff
pressure is increased before the cuff pressure is decreased at the
prescribed rate in measuring an actual blood pressure of the
subject and (b') a pressure value of the cuff at a time of
detection of the waveform during the increasing of the cuff
pressure.
In the automatic BP measuring apparatus in accordance with the
seventh aspect of the invention, the estimating means estimates,
according to the determined relationship, a BP value of the subject
based on (a') an evaluated value of the waveform of at least one
pulse of a pulse wave detected by the waveform detector while the
cuff pressure is increased before the cuff pressure is decreased
and (b') a pressure value of the cuff at the time of detection of
the waveform during the increasing of the cuff pressure. Thus, the
present apparatus quickly gives a doctor an estimated BP value of
the subject, even though the estimated value may be some or less
rough.
In a preferred embodiment in accordance with the seventh aspect of
the present invention, the BP measuring apparatus further comprises
evaluating means for evaluating a plurality of characteristics of
the waveform of the pulse wave detected by the waveform detector
during the decreasing of the cuff pressure, and providing an
evaluated value of each of the waveform characteristics, and the
determining means determines a plurality of relationships each
based on the evaluated value of a corresponding one of the waveform
characteristics and the estimating means calculates a plurality of
blood pressure values of the subject according to the determined
relationships, respectively, and estimates the blood pressure value
of the subject based on the calculated blood pressure values. In
this embodiment, since the estimated BP value of the subject is
provided based on a variety of BP values determined according to a
plurality of sorts of relationships, the reliability of the
estimated BP value is increased. The waveform characteristics may
comprise at least two selected from the pulse amplitude, Amp-b; the
maximum slope of the increasing portion of the waveform, SLOPE; the
degree of sharpness of the waveform, %MAP; the percentage of the
increasing portion of the waveform to the cyclic period thereof,
%IPP; and the percentage of the time difference between the primary
and secondary peaks of the waveform to the cyclic period thereof,
PI (peak index).
In another embodiment in accordance with the seventh aspect of the
present invention, the BP measuring apparatus further comprises
target pressure determining means for determining, based on the
estimated blood pressure value of the subject, a target pressure
value to which the cuff pressure is increased, and the pressure
changing device starts decreasing the cuff pressure after the cuff
pressure is increased to the target pressure. In this embodiment,
the cuff pressure is increased up to the target pressure that may
be higher by a prescribed value than an estimated systolic BP value
of the subject. Therefore, the cuff pressure is by no means
increased up to an unnecessarily high pressure relative to the
systolic BP value of the subject, or is by no means re-increased to
another target pressure higher than the first or initial target
pressure when the first target pressure is not sufficiently high.
Thus, the burden to the subject is reduced as such.
In another embodiment in accordance with the seventh aspect of the
present invention, the BP measuring apparatus further comprises:
abnormality identifying means for identifying a blood pressure
abnormality of the subject by comparing the estimated blood
pressure value of the subject with a reference value; and an output
device which outputs, when the blood pressure abnormality of the
subject is identified, information indicative of the identification
of the blood pressure abnormality of the subject. In this
embodiment, the output device informs a doctor of whether the blood
pressure the subject is abnormal, at an early stage when the cuff
pressure is increased before being decreased. Thus, the doctor can
make a quick decision on whether to give a medical treatment to the
subject.
According to an eighth aspect of the present invention, there is
provided an apparatus for automatically measuring a blood pressure
of a living subject, comprising: an inflatable cuff adapted to be
wound around a body portion of the subject, the cuff being inflated
to provide a cuff pressure to press the body portion; a pressure
sensor which detects the cuff pressure; a pressure changing device
which changes the cuff pressure; a blood pressure measuring device
which measures a blood pressure value of the subject by reading the
cuff pressure detected by the pressure sensor while the cuff
pressure is decreased at a prescribed rate by the pressure changing
device; a waveform detector which detects a waveform of a pulse
wave produced in the cuff during the decreasing of the cuff
pressure, the waveform of the pulse wave being changeable with the
cuff pressure; a memory which stores a pulse amplitude of the pulse
wave detected by the waveform detector, and a pressure value of the
cuff at a time of detection of the pulse amplitude; determining
means for determining an envelope representing a relationship
between (a) a plurality of pulse amplitudes detected by the
waveform detector while the cuff pressure is increased before the
cuff pressure is decreased at the prescribed rate and (b) a
plurality of pressure values of the cuff at respective times of
detection of the pulse amplitudes; and estimating means for
estimating a blood pressure value of the subject, based on the
determined envelope, according to a prescribed relationship.
In the automatic BP measuring apparatus in accordance with the
eighth aspect of the invention, the estimating means estimates a BP
value of the subject, based on the determined envelope, according
to a prescribed relationship between blood pressure and a
shape-related characteristic of an envelope. The prescribed
relationship is, e.g., such that two cuff-pressure values
respectively corresponding to two points on the envelope at which
the amplitudes of the envelope significantly largely change, are
estimated as the systolic and diastolic BP values of the subject,
like the relationship employed in the oscillometric BP determining
method. The present apparatus provides a doctor with the estimated
BP value of the subject, based on the envelope obtained during the
increasing of the cuff pressure before the decreasing of the same.
Thus, the doctor quickly obtains an estimated BP value of a
patient, even if the estimated value may be some or less rough.
It is an eighth object of the present invention to provide a blood
pressure measuring apparatus which determines a blood pressure
value of a living subject based on a series of smoothened wave
amplitudes and which enables a medical worker to easily judge
whether the condition of measurement of BP values is proper or
not.
The eight object has been achieved by the present invention.
According to a ninth aspect of the invention, there is provided an
apparatus for measuring a blood pressure of a living subject,
comprising: an inflatable cuff adapted to be wound around a body
portion of the subject, the cuff being inflated to provide a cuff
pressure to press the body portion; a pressure changing device
which changes the cuff pressure; a blood pressure measuring device
which (a) obtains a heartbeat-synchronous signal wave generated
from arteries of the body portion in synchronism with heartbeat of
the subject while the cuff pressure is changed by the pressure
changing device, (b) determines respective amplitudes of a
plurality of successive pulses of the heartbeat-synchronous signal
wave each of which corresponds to one cycle of heartbeat of the
subject, and provides, as a first series of determined pulse
amplitudes, the determined pulse amplitudes arranged in an order of
generation of the corresponding pulses, (c) smoothens the first
series of determined pulse amplitudes and thereby provides a second
series of smoothened pulse amplitudes, and (d) determines a blood
pressure value of the subject based on a change in the second
series of smoothened pulse amplitudes; an output device which
outputs a two-dimensional representation comprising a number of
picture elements; and a control device which controls the output
device to output the two-dimensional representation containing the
first series of determined pulse amplitudes and the second series
of smoothened pulse amplitudes such that one of the first and
second series of pulse amplitudes are superimposed on the other
series of pulse amplitudes.
In the BP measuring apparatus in accordance with the ninth aspect
of the invention, the output device outputs the two-dimensional
representation containing the first series of determined pulse
amplitudes and the second series of smoothened pulse amplitudes
such that one of the first and second series of pulse amplitudes
are superimposed on the other series of pulse amplitudes.
Therefore, a medical worker such a doctor can visually recognize
the differences between the first and second series of pulse
amplitudes in the two-dimensional representation. Those differences
result from external factors such as the physical motion of the
subject or the noise generated from peripheral devices. Based on
the total amount of the differences and the respective positions of
the differences with respect to the cuff pressure, the doctor can
easily judge whether the measured BP value contains a great error
due to the external factors, i.e., whether the condition of
measurement of the BP value is proper.
According to a tenth aspect of the present invention, there is
provided an apparatus for measuring a blood pressure of a living
subject, comprising: an inflatable cuff adapted to be wound around
a body portion of the subject, the cuff being inflated to provide a
cuff pressure to press the body portion; a pressure changing device
which changes the cuff pressure; a blood pressure measuring device
which (a) obtains a heartbeat-synchronous signal wave generated
from arteries of the body portion in synchronism with heartbeat of
the subject while the cuff pressure is changed by the pressure
changing device, (b) determines respective amplitudes of a
plurality of successive pulses of the heartbeat-synchronous signal
wave each of which corresponds to one cycle of heartbeat of the
subject, and provides, as a first series of determined pulse
amplitudes, the determined pulse amplitudes arranged in an order of
generation of the corresponding pulses, (c) smoothens the first
series of determined pulse amplitudes and thereby provides a second
series of smoothened pulse amplitudes, and (d) determines a blood
pressure value of the subject based on a change in the second
series of smoothened pulse amplitudes; an output device which
outputs a degree of propriety of a measurement condition under
which the blood pressure value of the subject is determined by the
blood pressure measuring device; calculating means for calculating
a degree of correction of the second series of smoothened pulse
amplitudes from the first series of determined pulse amplitudes, by
calculating a ratio of (a) respective differences between (a1) the
determined pulse amplitudes corresponding to respective pressure
values of the cuff within a prescribed pressure range and (a2) the
corresponding smoothened pulse amplitudes, to (b) at least one of
the determined pulse amplitudes and the corresponding smoothened
pulse amplitudes; and a control device which controls the output
device to output the degree of propriety of the measurement
condition which corresponds to the degree of correction of the
second series of pulse amplitudes calculated by the calculating
means.
In the BP measuring apparatus in accordance with the tenth aspect
of the invention, the output device outputs the degree of propriety
of the measurement condition which corresponds to the degree of
correction of the second series of pulse amplitudes calculated by
the calculating means. Thus, a medical worker can visually
recognize the degree of propriety of the condition of BP
measurement. By comparing the degree of correction reflecting the
amount of external factors, with a prescribed reference value, the
present apparatus may automatically judge whether the measured BP
value contains a great error due to the external factors, i.e.,
whether the condition of measurement of the BP value is proper.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and optional objects, features, and advantages of the
present invention will be better understood by reading the
following detailed description of the preferred embodiments of the
invention when considered in conjunction with the accompanying
drawings, in which:
FIG. 1 is a perspective view of a blood pressure (BP) measuring
apparatus embodying the present invention;
FIG. 2 is a diagrammatic view of the electric arrangement of the
apparatus of FIG. 1;
FIG. 3 is a flow chart representing a control program according to
which the apparatus of FIG. 1 operates;
FIG. 4 is a view illustrating an evaluated value, %MAP,
representing a characteristic of the waveform of pulse wave, the
value %MAP being determined at Step S8 of FIG. 3;
FIG. 5 is a view of a printed output of the apparatus of FIG. 1 as
a result of an operation of the same according to the flow chart of
FIG. 3;
FIG. 6 is a view of a printed output of another BP measuring
apparatus obtained by modifying the apparatus of FIG. 1;
FIG. 7 is a view of a printed output of yet another BP measuring
apparatus obtained by modifying the apparatus of FIG. 1;
FIG. 8 is a diagrammatic view corresponding to FIG. 2, showing the
electric arrangement of a BP measuring apparatus as a second
embodiment of the present invention;
FIG. 9 is a flow chart representing a control program according to
which the apparatus of FIG. 8 operates in a BP evaluation mode;
FIG. 10 is a view corresponding to FIG. 5, showing a printed output
of the apparatus of FIG. 8 as a result of an operation of the same
according to the flow chart of FIG. 9, in the case where measured
BP values are normal;
FIG. 11 is a view corresponding to FIG. 10, showing another printed
output of the apparatus of FIG. 8, in the case where measured BP
values are somewhat abnormal;
FIG. 12 is a view corresponding to FIG. 10, showing yet another
printed output of the apparatus of FIG. 8, in the case where
measured BP values are abnormal;
FIG. 13 is a flow chart corresponding to FIG. 9, representing
another control program according to which the apparatus of FIG. 8
operates;
FIG. 14 is a flow chart corresponding to FIG. 9, representing yet
another control program according to which the apparatus of FIG. 8
operates;
FIG. 15 is a flow chart corresponding to FIG. 9, representing
another control program according to which the apparatus of FIG. 8
operates either in a random image output mode or in a time-related
image output mode;
FIG. 16 is a flow chart corresponding to FIG. 9, representing yet
another control program according to which the apparatus of FIG. 8
operates in an image/comment edit mode;
FIG. 17 is a side view of a BP measuring apparatus as a third
embodiment of the present invention;
FIG. 18 is a diagrammatic view of a partly structural and partly
electric arrangement of the apparatus of FIG. 17, showing an
arm-receiver positioning device and a misalignment detector;
FIG. 19 is a view of a cylinder drive device of the apparatus of
FIG. 17;
FIG. 20 is a view of another arm-receiver positioning device which
may be employed in the apparatus of FIG. 17;
FIG. 21(A) is a front view of another misalignment detector which
may be employed in the apparatus of FIG. 17;
FIG. 21(B) is a cross section of the misalignment detector of FIG.
21(A) taken along Line 21(B)--21(B);
FIG. 22 is a view of yet another arm-receiver positioning device
and yet another misalignment detector which may be employed in the
apparatus of FIG. 17;
FIG. 23 is a diagrammatic view of a BP monitor apparatus as a
fourth embodiment of the present invention;
FIG. 24 is a flow chart representing a first half of a control
program according to which the apparatus of FIG. 23 operates;
FIG. 25 is a flow chart representing a second half of the control
program of FIG. 24;
FIG. 26 is a view showing a linear function defining a relationship
between pulse amplitude and blood pressure, the function being
determined in a step of the flow chart of FIG. 24;
FIG. 27 is a time chart representing the time change of cuff
pressure P.sub.c when the monitor apparatus of FIG. 23 operates
according to the flow charts of FIGS. 24 and 25;
FIG. 28 is a view explaining a manner in which a rate of change
.theta. of pulse amplitudes A.sub.m with respect to cuff pressures
P.sub.c is calculated in a step of the flow chart of FIG. 25;
FIG. 29 is a view showing the respective envelopes of pulse
amplitudes of a living subject having a normal blood pressure, a
subject suffering an abnormally low blood pressure, and a subject
being in a shock state;
FIG. 30 is a flow chart representing steps which may be carried out
in place of Step S117 of FIG. 25 by the monitor apparatus of FIG.
23;
FIG. 31 is a time chart representing the time change of cuff
pressure P.sub.c when the monitor apparatus of FIG. 23 operates
according to the flow chart of FIG. 30;
FIG. 32 is a flow chart representing steps which may be carried out
in addition to the steps of FIGS. 24 and 25 by the monitor
apparatus of FIG. 23;
FIG. 33 is a view showing a relationship which is utilized in a
step of the flow chart of FIG. 32;
FIG. 34 is a diagrammatic view of a BP measuring apparatus as a
fifth embodiment of the present invention;
FIG. 35(A) is a view showing an example of a pulse waveform
obtained from a cuff wound around a body portion of a living
subject when the cuff pressure is taking a value around a systolic
blood pressure of the subject;
FIG. 35(B) is a view showing a pulse waveform obtained from the
cuff when the cuff pressure is taking a value around a mean blood
pressure of the subject;
FIG. 35(C) is a view showing a pulse waveform obtained from the
cuff when the cuff pressure is taking a value around a diastolic
blood pressure of the subject;
FIG. 36 is a flow chart representing a first half of a control
program according to which the apparatus of FIG. 34 operates;
FIG. 37 is a flow chart representing a second half of the control
program of FIG. 36;
FIG. 38 is a time chart representing the change of cuff pressure
P.sub.c in a BP measurement and the change of pulse amplitudes in
relation with the change of cuff pressure P.sub.c ;
FIG. 39 is a view explaining the respective definitions of various
waveform characteristics determined by the apparatus of FIG. 34 to
evaluate a pulse waveform;
FIG. 40 is a view explaining a relationship between blood pressure
(i.e., cuff pressure values P.sub.c as the measured blood pressure
values) and each of the waveform characteristics;
FIG. 41 is a view explaining a relationship between cuff pressure
P.sub.c and pulse amplitude Amp-b;
FIG. 42 is a view explaining a relationship between cuff pressure
P.sub.c and waveform slope SLOPE;
FIG. 43 is a view explaining a relationship between cuff pressure
P.sub.c and evaluated value %MAP;
FIG. 44 is a view explaining a relationship between cuff pressure
P.sub.c and evaluated value %IPP;
FIG. 45 is a view explaining a relationship between cuff pressure
P.sub.c and evaluated value PI;
FIG. 46 is a flow chart representing a first half of a modified
control program according to which the apparatus of FIG. 34
operates;
FIG. 47 is a time chart representing a second half of the modified
control program of FIG. 46;
FIG. 48 is a view explaining a first envelope H.sub.1 representing
a relationship between cuff pressure values P.sub.c and pulse
amplitudes PA, the pulse amplitudes being obtained while the cuff
pressure P.sub.c is slowly decreased according to the flow chart of
FIG. 46;
FIG. 49(A) is a view explaining a first example of a second
envelope H.sub.2 representing a relationship between cuff pressure
values P.sub.c and pulse amplitudes PA, the pulse amplitudes being
obtained while the cuff pressure P.sub.c is quickly increased
according to the flow chart of FIG. 47;
FIG. 49(B) is a view explaining a second example of the second
envelope H.sub.2 ;
FIG. 49(C) is a view explaining a third example of the second
envelope H.sub.2 ;
FIG. 49(C) is a view explaining a fourth example of the second
envelope H.sub.2 ;
FIG. 50 is a diagrammatic view of an automatic BP measuring
apparatus as a sixth embodiment of the present invention;
FIG. 51 is a flow chart representing a control program according to
which the apparatus of FIG. 50 operates;
FIG. 52 is a flow chart representing the steps carried out in the
subroutine of Step S305 of FIG. 51;
FIG. 53 is a view of an example of a pulse-amplitude indication
(i.e., a series of detected pulse amplitudes and a series of
smoothened pulse amplitudes) and a measurement-condition indication
both of which are output by an output device of the apparatus of
FIG. 50;
FIG. 54 is a view corresponding to FIG. 53, showing another example
of a series of detected pulse amplitudes and a series of smoothened
pulse amplitudes output by the apparatus of FIG. 50;
FIG. 55 is a view corresponding to FIG. 53, showing yet another
example of a series of detected pulse amplitudes and a series of
smoothened pulse amplitudes output by the apparatus of FIG. 50;
FIG. 56 is a view corresponding to FIG. 53, showing yet another
example of a series of detected pulse amplitudes and a series of
smoothened pulse amplitudes output by the apparatus of FIG. 50;
FIG. 57 is a view corresponding to FIG. 53, showing yet another
example of a series of detected pulse amplitudes and a series of
smoothened pulse amplitudes output by the apparatus of FIG. 50;
FIG. 58 is a view of another example of a measurement-condition
indication output by the apparatus of FIG. 50; and
FIG. 59 is a flow chart including steps carried out to select and
output an evaluation message corresponding to a determined
correction degree C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring first to FIG. 1, there is shown an automatic blood
pressure (BP) measuring apparatus 8 embodying the present
invention. In the figure, reference numeral 10 designates a housing
of the BP apparatus 8. The BP apparatus 8 includes a tunnel-like,
cylindrical hollow section which serves as an arm receiver 14 into
which a living subject such as a patient inserts his or her arm 12
for measurement of his or her blood pressure value. Inside the arm
receiver 14, an elongate belt 18 is supported such that the belt 18
takes a generally cylindrical shape. An inflatable cuff 16
constituted by a bag-like flexible cloth and a rubber bag enveloped
in the flexible cloth, is secured to the inner surface of the
elongate belt 18. The BP apparatus 8 has an operation panel 20
including a START switch 22, a STOP switch 24, a printer 26, and a
card insertion slot 28. The BP apparatus 8 also has a display panel
30 including a SAP display 32, a DAP display 34, a PR display 36,
and a date and time display 38. The abbreviations `SAP`, `DAP`, and
`PR` represent a systolic and a diastolic blood pressure and a
pulse rate, respectively. The BP apparatus 8 has a speaker 40
provided in the side wall thereof. The speaker 40 issues various
sound messages.
FIG. 2 shows the electric arrangement of the BP apparatus 8. As
shown in the figure, the inflatable cuff 16 is connected via piping
48 to a pressure sensor 42, a cuff-pressure regulator valve 44, and
an air pump 46. The elongate belt 18, which takes a cylindrical
shape in the arm receiver 14 and to which the inflatable cuff 16 is
secured, is fixed at one of the longitudinal ends thereof to the
housing 10 and is connected at the other longitudinal end to a
rotatable drum 52 which is driven or rotated by a direct-current
(DC) motor 50 via reduction gears. The elongate belt 18 or
inflatable cuff 16 is tightened, and loosened, by the DC motor
50.
The output signal of the pressure sensor 42 is fed to a band-pass
filter 54 which selectively transmits a heartbeat-synchronous
oscillatory component of the received pressure signal, as a pulse
wave signal, SM, to an analog to digital (A/D) converter 58 of an
arithmetic and control circuit 56. The pulse wave signal SM
represents the pulse wave produced from the pressed arteries of the
subject's arm 12 and propagated to the inflatable cuff 16 currently
pressing the arm 12. The pressure signal of the pressure sensor 42
is also fed to a low-pass filter 60 which selectively transmits a
static component of the received signal, as a cuff pressure signal,
SK, to the A/D converter 58 of the control circuit 56. The cuff
pressure signal SK represents the change of static pressure of the
inflatable cuff 16.
The arithmetic and control circuit 56 is essentially constituted by
a microcomputer including a central processing unit (CPU) 62, a
read only memory (ROM) 64, a random access memory (RAM) 66, an
input interface circuit 68, an output interface circuit 70, and
data bus 61. The CPU 62 processes input signals according to the
control programs pre-stored in the ROM 64 by utilizing the
temporary-storage function of the RAM 66, and produces drive
signals and display signals. For blood pressure measurement, the
CPU 62 feeds drive signals to the DC motor 50 to tightly wind the
inflatable cuff 16 around the upper arm 12 of the living subject
being currently inserted in the arm receiver 14, subsequently to
the air pump 46 to inflate the cuff 16 and thereby press the upper
arm 12, and then to the cuff-pressure regulator valve 44 to
gradually reduce the cuff pressure of the cuff 16, so that the CPU
62 receives during reduction of the cuff pressure the pulse wave
signal SM and the cuff pressure signal SK from the pressure sensor
42 via the respective filters 54, 60, determines based on the
received signals SM, SK the SAP and DAP blood pressure values of
the subject in the known oscillometric BP measuring process, feeds
display signals to the SAP and DAP displays 32, 34 to indicate the
determined SAP and DAP values, respectively, and stores the SAP and
DAP values in a blood-pressure (BP) memory area 87 of a memory
device 86. The cuff 16, air pump 46, pressure sensor 42, filters
54, 60, and control device 56 cooperate with each other to provide
a BP measuring device 100.
The BP memory area 87 of the memory device 86 is capable of storing
a number of sets of blood pressure data each of which represents a
pair of SAP and DAP values obtained in a corresponding one of a
number of blood pressure measurements of the living subject. The
memory device 86 also includes a waveform memory area 88. The CPU
62 stores, in the waveform memory area 88, a waveform of the pulse
wave signal SM obtained at a prescribed pressure, for example, a
mean blood pressure (MAP) value of the subject or a certain
pressure lower than the MAP value, in each of the blood pressure
measurements of the subject. Furthermore, the memory device 86
includes an evaluated-value (EV) memory area 89. The CPU 62
evaluates a characteristic of each of the waveforms of the pulse
wave signal SM stored in the waveform memory area 88, provides an
evaluated value of each waveform, and stores in the EV memory area
89 the evaluated value of the waveform in each of the blood
pressure measurements of the subject. The memory device 86 may be a
well known memory device such as a magnetic disk, magnetic tape,
volatile semiconductor memory, or non-volatile semiconductor
memory.
In each of blood pressure measurements, the CPU 62 operates the
printer 26 to record, on a recording sheet 110 (FIG. 5), graphical
representations 116 representing the BP values accumulatively
stored in the BP memory area 87 and the waveform evaluated values
accumulatively stored in the EV memory area 89. In each blood
pressure measurement, the CPU 62 controls the printer 26 to
additionally print, on the recording sheet 110, waveform
representations 118 including curves 122 representing the waveforms
accumulatively stored in the waveform memory area 88, along a time
axis 124 identical with a common time axis 120 of the graphs
116.
The BP memory area 87 of the memory device 86 stores a number of
pairs of SAP and DAP values of the living subject that are measured
using the inflatable cuff 16, air pump 46, pressure sensor 42, etc.
The band-pass filter 54 provides the pulse wave signal SM
representing the pulse wave produced from the arteries of the arm
12 of the subject in synchronism with the heartbeats of the subject
while the cuff pressure of the cuff 16 is gradually decreased in
each blood pressure measurement. The waveform memory area 88 stores
the waveform of the pulse wave signal SM provided by the band-pass
filter 54, in each blood pressure measurement. The printer 26
outputs the BP values accumulatively stored in the BP memory area
87, in the order of measurement of those BP values, and outputs the
curves 122 representing the waveforms accumulatively stored in the
waveform memory area 88, in the order of storage of those waveforms
and in parallel to the BP values. Thus, the present BP apparatus 8
is very easy to use, and outputs the BP values and waveforms of the
living subject in a side-by-side relation with each other. Medical
workers can read the change of the waveforms in relation with the
change of the BP values, and can make a diagnosis on whether the
subject has a heart disease.
The ROM 64 stores a control program represented by a flow chart
shown in FIG. 3. The flow chart includes Step S10 at which the CPU
62 processes or modifies the waveforms of the pulse wave signals SM
stored in the waveform memory area 88 of the memory device 86, so
that the respective amplitudes of the modified waveforms are equal
to one another and the thus modified waveforms are output on the
recording sheet 110 by the printer 26. Thus, medical workers can
compare the waveforms with one another and recognize the time
change of the waveforms.
The flow chart of FIG. 3 also includes Step S11 at which the CPU 62
processes or modifies the waveforms of the pulse wave signals SM
stored in the waveform memory area 88, so that the respective
wavelengths of the modified waveforms are equal to one another and
the thus modified waveforms are output on the recording sheet 110
by the printer 26. Thus, medical workers can compare the waveforms
with one another and recognize the time change of the
waveforms.
The flow chart of FIG. 3 further includes Step S8 at which the CPU
62 evaluates a characteristic of each of the waveforms
accumulatively stored in the waveform memory area 88, provides an
evaluated value of the characteristic of each waveform and stores,
in the EV memory area 89, the evaluated value of each waveform. The
printer 26 outputs the respective evaluated values of the waveforms
that have accumulatively been stored in the EV memory area 89, in
the order of storage of the waveforms in the waveform memory area
88. Thus, medical workers can quantitatively understand the time
change of the pulse wave signals SM and can easily recognize the
time change of the respective waveforms of the pulse wave signals
SM.
The printer 26 outputs the respective graphs 116 of (a) the BP
values accumulatively stored in the BP memory area 87 and (b) the
waveform evaluated values accumulatively stored in the EV memory
area 89, each along the common time axis 120. In addition, the
printer 26 outputs the curves 122 representing the waveforms
accumulatively stored in the waveform memory area 88, in parallel
with the above two graphs, along the identical time axis 124. That
is, the printer 26 outputs the BP values and the waveform evaluated
values, together with the corresponding waveform curves, along the
common time axis. Thus, medical workers can easily recognize the
time change of the waveforms of the pulse waves of the living
subject.
The CPU 62 is connected to a card reader 74 which receives a
magnetic card 76 being inserted in the card slot 28 by the living
subject and read identification (ID) data recorded on the magnetic
card 76. The ID data recorded on the magnetic card 76 identifies
the living subject carrying the magnetic card 76.
Hereinafter, there will be described the operation of the present
automatic BP measuring apparatus 8 constructed as described above,
by reference to the flow chart of FIG. 3.
First, at Step S1, the CPU 62 judges whether a magnetic card 76 has
been inserted in the card reader 74 through the card slot 28. If a
negative judgment is made at Step S1, the current control cycle of
this routine is ended. On the other hand, if a positive judgment is
made, i.e., if a magnetic card 76 has been inserted, the control of
the CPU 62 proceeds with Step S2 to read the ID data magnetically
recorded on the magnetic card 76. The magnetic card 76 may be a
product according to Japanese Industrial Standard, X6301 or
X6302.
Step S2 is followed by Step S3 to judge whether the ID data read
from the magnetic card 76 has been registered in the BP apparatus
8, i.e., is identical with any of the sets of ID data stored in an
ID data memory area (not shown) of the memory device 86. If a
negative judgment is made at Step S3, the control goes to Step S12
at which the CPU 62 controls the printer 26 to output, on a
recording sheet 110, a message indicating that the ID data recorded
on the magnetic card 76 has not been registered on the BP apparatus
8 and that you are requested to register your magnetic card 76 on
the BP apparatus 8. In addition, the CPU 62 controls the card
reader 74 to eject the non-registered card 76.
On the other hand, if a positive judgment is made at Step S3, the
control of the CPU 62 goes to Step S4 to judge whether the START
switch 22 has been operated to start a blood pressure (BP)
measurement. The CPU 62 repeats Step S4 until a positive judgment
is made. If a positive judgment is made at Step S4, the control
goes to Step S5, i.e., BP measure subroutine in which a systolic
(SAP), a diastolic (DAP), and a mean blood pressure (MAP), and a
pulse rate (PR) value, of the living subject are measured or
determined. In the BP measure subroutine, the CPU 62 operates,
according to a pre-stored algorithm, for automatically increasing
the cuff pressure of the inflatable cuff 16 and determining during
the reduction of the cuff pressure the SAP, DAP, and MAP values of
the living subject in the known oscillometric BP measuring method.
Specifically, the SAP and DAP values are determined based on the
change of respective amplitudes of pulses of the pulse wave signal
SM obtained during the reduction of the cuff pressure. The MAP
value is determined as being equal to a cuff pressure at the time
of occurrence of a pulse having a maximum amplitude. The PR value
is determined based on a time difference between two successive
pulses of the pulse wave signal SM, i.e., pulse wave represented by
the signal SM.
Step S5 is followed by Step S6 to store, in the BP memory area 87
of the memory device 86, data indicative of the SAP, DAP, MAP and
PR values determined at Step S5, together with data indicative of
the date and time of measurement of those values, in relation with
the ID data identifying the magnetic card 76 being currently
inserted in the card reader 74 and thereby identifying the living
subject carrying the card 76. Additionally, the CPU 62 commands the
SAP, DAP, and PR displays 32, 34, 36 to display the determined SAP,
DAP, and PR values, respectively.
At the following Step S7, the CPU 62 stores, in the waveform memory
area 88, the waveform of one of the pulses of the pulse wave signal
SM which one pulse has been detected at a prescribed cuff pressure,
or in a prescribed range of the cuff pressure, during the reduction
of the cuff pressure. The waveform of one pulse is stored together
with data indicative of the date of detection of the pulse wave
signal SM, both in relation with the ID data identifying the living
subject carrying the ID card 76. The prescribed cuff pressure at
which the waveform is detected or obtained may be selected at
around the MAP value of the subject, or at a pressure lower than
the MAP value, or at the lowest possible pressure in a pressure
range between the MAP and DAP values of the subject. For example,
the CPU 62 selects, from all the pulses obtained between the MAP
and DIA values, one pulse obtained at the lowest pressure of all
the pressures at which the respective pulses are obtained. The CPU
62 stores the waveform of the thus selected one pulse in the
waveform memory 86. To this end, the CPU 62 utilizes the pulse wave
signal SM supplied from the band-pass filter 54.
Step S7 is followed by Step S8 to evaluate a characteristic of the
waveform of one pulse SM stored in the waveform memory area 88, and
provide an evaluated value of the waveform characteristic of one
pulse SM. The evaluate value may be one or both of (a) a slope
value, SLOPE, related to an increasing portion of one pulse
starting from a lower peak to a following upper peak of the signal
SM, and (b) an MAP percentage value, %MAP, related to a decreasing
portion of one pulse starting from an upper peak to a following
lower peak of the signal SM. The value SLOPE is defined as the
greatest slope, (dP/dt).sub.max, of the increasing portion of one
pulse SM. The value %MAP is defined as the percentage
(=100.times.a/b) of the MAP value (i.e., height, a, of the MAP
value shown in FIG. 4) with respect to the amplitude, b, of one
pulse SM (b is the pressure difference between the SAP and DAP
values). The value SLOPE reflects the strength of the heart muscle
of the living subject, and relates to the amount of output of the
heart of the subject. The value %MAP relates to the diastolic
period of the heart of the subject, i.e., resistance of the
peripheral arterial vessels of the subject.
At the following Step S9, the CPU 62 stores, in the EV memory area
89, the waveform characteristic evaluated values determined at Step
S8, i.e., the two values SLOPE, %MAP, with the date of detection of
the pulse wave signal SM, in relation with the ID data identifying
the living subject. Step S9 is followed by Step S10 to modify the
one-pulse waveform stored in the waveform memory area 88 so that
the modified waveform takes a prescribed amplitude, i.e.,
prescribed difference between the upper and lower peaks of the
waveform. Since amplitudes of waveforms easily change depending
upon the cuff pressures at which the waveforms are obtained through
the cuff 16, the amplitude modification of the waveforms at Step
S10 ensures that the waveforms are clearly output in parallel with
one another on the recording sheet 110 and that medical workers
easily compare those waveforms with one another.
At the following Step S11, the CPU 62 modifies the one-pulse
waveform whose amplitude has been modified at Step S10, so that the
modified waveform takes a prescribed wavelength, i.e., prescribed
time length between the two successive lower peaks of the waveform.
Since wavelengths of waveforms easily change depending upon the
pulse rates at which the waveforms are obtained through the cuff
16, the wavelength modification of the waveforms at Step S11
ensures that the waveforms are clearly output in parallel with one
another on the recording sheet 110 and that medical workers easily
compare those waveforms with one another.
Step S11 is followed by Step S12 to control the printer 26 to
output or record, on the recording sheet 110 shown in FIG. 5, the
BP and PR data which have accumulatively been stored in the memory
device 86 in relation with the ID data read from the magnetic card
76. Specifically, in a left-hand and upper portion of the sheet
110, the printer 26 records a name 112 of the living subject
identified by the ID data. Beneath the name 112, the printer 26
records (a) a data list 114 including the dates and times of
measurement and the measured SAP, DAP, and RP values; (b) graphic
representations 116 of various parameters; and (c) waveform
representations 118. The graphic representations 116 include (b1) a
series of bars the upper and lower ends of each of which represent
an SAP and a DAP blood pressure value, (b2) a series of symbols,
.DELTA., each of which represents a PR value, (b3) a series of
symbols, .smallcircle., each of which represents a value SLOPE, and
(b4) a series of symbols, .cndot., each of which represents a value
%MAP, all in relation with corresponding times of measurement,
along the common axis of abscissae, i.e., first time axis 120. The
waveform representations 118 include a series of curves 122
representing the waveforms accumulatively stored in the waveform
memory area 88, each in relation with the time of measurement of
corresponding BP values, along the first time axis 120 and the
second time axis 124 identical with the first time axis 120.
As is apparent from the foregoing description of the first
embodiment, the band-pass filter 54 of the BP apparatus 8 provides
a pulse wave signal SM representing a pulse wave produced from
arteries of a living subject in synchronism with the heartbeats of
the subject while each blood pressure measurement is carried out on
the subject at Step S5 of FIG. 3. The waveform of one pulse of the
pulse wave signal SM provided by the band-pass filter 54 is
accumulatively stored in the waveform memory area 88 at Step S7. At
Step S12, the printer 26 outputs (a) the BP values accumulatively
stored in the BP memory area 87, in the order of measurement, on
the recording sheet 110, and (b) the curves 122 representing the
waveforms accumulatively stored in the waveform memory area 88, in
the order of storage, in parallel with the BP values, both along
the common time axis 120. The BP measuring apparatus 8 is very easy
to operate and simultaneously outputs the BP values and waveforms
of a living subject in parallel with each other. Medical workers
can easily recognize a time change of the waveforms in relation
with a time change of the BP values, and can make a diagnosis on
whether the subject has a heart disease or not.
In the first embodiment, the band-pass filter 54 is primarily
employed for extracting, as a pulse wave signal SM, a pressure
oscillation produced in the cuff 16 in synchronism with the
heartbeats of a living subject in a blood pressure measurement, and
the CPU 62 is programmed to utilize the waveform of the pulse wave
signal SM provided by the band-pass filter 54. Thus, the BP
apparatus 8 does not require an exclusive sensor for detecting a
pulse wave from the subject, and enjoys a simpler construction and
a lower manufacturing cost.
In the first embodiment, the CPU 62 modifies, at Step S10 of FIG.
3, each waveform stored in the waveform memory area 88, in such a
way that each modified waveform has a prescribed amplitude, and the
printer 26 outputs at Step S12 the modified waveforms each having
the prescribed amplitude. Thus, medical workers can easily compare
the output waveforms with one another and recognize a time change
of the waveforms.
Also, in the first embodiment, the CPU 62 modifies, at Step S11,
each waveform stored in the waveform memory area 88, in such a way
that each modified waveform has a prescribed wavelength, and the
printer 26 outputs at Step S12 the thus modified waveforms each
having the prescribed wavelength. Thus, medical workers can easily
compare the output waveforms with one another and recognize a time
change of the waveforms.
Moreover, in the first embodiment, the CPU 62 evaluates, at Step
S8, a characteristic of each waveform stored in the waveform memory
area 88, provides an evaluated value of each waveform, and stores
the waveform evaluated value in the EV memory area 89. At Step S12,
the printer 26 outputs the waveform evaluated values accumulatively
stored in the EV memory area 89, in the order of evaluation, i.e.,
in the order of detection of waveform. Thus, medical workers can
recognize a quantitative change of the waveforms and more easily
recognize a time change of the waveforms.
Furthermore, in the first embodiment, the printer 26 outputs, in
the graphs 116, the BP values accumulatively stored in the BP
memory area 87, and the waveform evaluated values accumulatively
stored in the EV memory area 89, along the common first time axis
120. Simultaneously, the printer 26 outputs the curves 122
corresponding to the waveforms accumulatively stored in the
waveform memory area 88, in parallel with the graphs 116, along the
first or second time axis 120, 124. Thus, medical workers can still
more easily recognize a time change of the waveforms.
The BP apparatus 8 or the printer 26 may be modified to record, at
Step S12, measurement data 112, 114, 126, 128 on a recording sheet
125 as shown in FIG. 6. The recording sheet 125 has a width greater
than that of the recording sheet 110 shown in FIG. 5.
Alternatively, the BP apparatus 8 may further include a display
device, such as a cathode ray tube (CRT), for displaying the same
visual representation as that recorded on the recording sheet 125
of FIG. 6. In a left-hand and upper portion of the recording sheet
125, the printer 26 records a name 112 of a living subject
identified by the ID data read from a magnetic card 76. The printer
26 records, beneath the name 112, a data list 114 including dates
and times of measurement and measured SAP, DAP, and RP values; and,
on the right-hand side of the data list 114, graphic
representations 126 of various parameters, and waveform
representations 128. The graphic representations 126 show a series
of bars the right and left ends of each of which represent an SAP
and a DAP value (mmHg), a series of symbols, .gradient., each of
which represents a PR value, a series of symbols, .smallcircle.,
each of which represents a value SLOPE, and a series of symbols,
.circle-solid., each of which represents a value %MAP, all in
relation with corresponding times of measurement, along a common
axis of ordinates, i.e., time axis 130. The waveform
representations 128 include a series of curves 132 representing the
waveforms accumulatively stored in the waveform memory area 88,
each in relation with the time of measurement of corresponding BP
values, along the time axis 130. The time axis 130 need not be
explicitly indicated on the recording sheet 125, but may be
provided implicitly, without any indication thereof, on the sheet
125. Between the waveforms 128 and the graphs 126, the recording
sheet 125 shows a series of values %MAP and a series of values
SLOPE. The left-hand value "13" of, e.g., a measurement result
"13-5" of the SLOPEs represents a maximum slope of the increasing
portion of one pulse, whereas the right-hand value "5" represents a
maximum slope of the decreasing portion of the same pulse.
Otherwise, the BP apparatus 8 or the printer 26 may be modified to
record, at Step S12, measurement data 112, 134, 136, 138 on a
recording sheet 135 as shown in FIG. 7. In a left-hand and upper
portion of the recording sheet 135, the printer 26 records a name
112 of a living subject identified by the ID data read from a
magnetic card 76. The printer 26 records, beneath the name 112, a
data list 134 including dates and times of measurements and
measured SAP, DAP, and RP values; and, on the right-hand side of
the data list 134, graphic representations 136 of various
parameters, waveform representations 138, and names 146 of
administered medicines. The graphic representations 136 show a
series of bars the right and left ends of each of which represent a
SAP and a DAP blood pressure value (mmHg), and a series of symbols,
.smallcircle., each of which represents a PR value, all in relation
with corresponding times of measurements, along a common axis of
ordinates, i.e., time axis 140. The waveform representations 138
include, in a ruled area 148, a series of curves 142 representing
the waveforms accumulatively stored in the waveform memory area 88,
each in relation with the time of measurement of corresponding SAP
and DAP values, along a time axis 144 as one side of the ruled area
148 and additionally along the time axis 140. The names of
administered medicines 146 indicate the medicines administered to
the living subject when blood pressure measurements are carried out
on the subject. Data representing the medicine names 146 may be
input to the BP apparatus 8 through operation of a keyboard (not
shown) connected to the apparatus 8, or may be transmitted from a
host computer (not shown) which processes medical information on
the living subject. The medicine data may be input or transmitted
to the control circuit 56 of the BP apparatus 8 before Step S4 of
FIG. 3.
Since the medicine names 146 are indicated together with the graphs
136 and waveforms 138, medical workers can recognize the time
changes of medical effects of the medicines administered to the
subject to treat the subject's heart disease. The rules 148 are
provided for enabling the medical workers to more easily read the
time change of the waveforms 142. However, the rules 148 may be
omitted. In the data list 134, the size of the figures representing
the PR values are smaller than that of the figures representing the
BP values, for preventing any confusion of the BP and PR values.
However, the BP and RP values may be recorded in the same size.
It is to be understood that in the first embodiment the BP
apparatus 8 may be modified in various manners.
In the first embodiment relating to the BP apparatus 8, it is
possible to omit all steps, or one or more specific steps, out of
Steps S8 through S11 of the flow chart of FIG. 3.
In the flow chart of FIG. 3, it is possible to carry out Steps S10
and S11 before Step S7. In this case, at Step S7, the CPU 62
stores, in the waveform memory area 88, the waveforms which had
been modified with respect to the amplitudes and wavelengths
thereof at Steps S10 and S11.
At Step S5 of FIG. 3, the CPU 62 determines BP values according to
the known oscillometric method. However, the BP apparatus 8 may be
modified to measure BP values of a living subject according to the
known Korotkoff-sound method where one or more BP values are
determined based on detected Korotkoff sounds. In this case, the BP
apparatus 8 is provided with a microphone which detects Korotkoff
sounds produced from arteries of a body portion (e.g., upper arm)
of a living subject while the cuff pressure pressing the upper arm
is changed, i.e., gradually decreased or increased.
The automatic BP measuring apparatus 8 starts measuring BP values
of a living subject if ID data recorded on a magnetic card 76 being
inserted therein by the subject is found to be identical with ID
data already registered in the apparatus 8. However, the principle
of the present invention is applicable to other types of BP
measuring apparatus, for example, apparatus which continuously
repeats BP measurements of a living subject at regular intervals of
time (e.g., at a prescribed interval of 5 to 30 minutes) by using
an inflatable cuff being wound around a body portion of the
subject. In this case, the apparatus may have a display device
(e.g., CRT) which displays the repetitively measured BP values, and
the waveforms obtained therewith, along a common time axis.
Next, there will be described a second embodiment of the present
invention. The second embodiment relates a blood pressure (BP)
measuring apparatus 208 having an electric arrangement shown in
FIG. 8. The BP measuring apparatus 208 is similar to the BP
measuring apparatus 8 shown in FIGS. 1 and 2. Therefore, the same
reference numerals as used in FIGS. 1 and 2 are used to designate
corresponding elements or parts of the BP apparatus 208, and the
description of those elements or parts is omitted. The following
description will be focused on the differences of the BP apparatus
208 from the BP apparatus 8.
In the blood pressure and pulse rate (PR) measuring process, the BP
apparatus 208 operates similar to the BP apparatus 8. Specifically,
a CPU 62 of an arithmetic and control device 56 feeds drive signals
to a DC motor 50, subsequently to an air pump 46, and then to a
cuff-pressure regulator valve 44, so that the CPU 62 receives a
pulse wave signal SM and a cuff pressure signal SK from a pressure
sensor 42 via respective filters 54, 60, determines based on the
received signals SM, SK the BP and PR values of a living subject 12
such as a patient according to known algorithms pre-stored in the
ROM 64, feeds display signals to an SAP, a DAP, and a PR display
32, 34, 36 to display the measured BP and PR values, and generates
print signals to a printer 26 to record the measured values on
recording sheets 292a, 292b, and 292c respectively shown in FIGS.
10, 11, and 12.
In the present embodiment, the CPU 62 accumulatively stores the
measured BP and PR values of the subject 12, in a
physical-information (PI) memory area 284 of a memory device 280
connected to the control device 56. The memory device 280 may be
constituted by a magnetic disk, a magnetic tape, or a semiconductor
memory.
The control device 56 or CPU 62 is connected to a speaker drive
circuit 277 which supplies drive signals to a speaker 40 to
generate sounds or voices such as messages to the subject 12 or
medical workers. The CPU 62 is also connected to a known image
reader 278 which reads images from an original bearing an original
image.
The memory device 280 includes an evaluation-comment (EC) memory
area 282 in which are pre-stored a plurality of sets of
evaluation-comment data each of which is indicative of a
corresponding one of a plurality of predetermined BP evaluation
comments relating to the blood pressure of the subject 12, or the
time change of the BP values accumulatively stored in the PI memory
area 284. The CPU 62 selects, according to the control programs
pre-stored in the ROM 64, one of the stored evaluation comments
which corresponds to the BP values of the subject 12 measured by a
BP measuring device 100 in a current operation cycle, and/or the
collected BP values of the subject 12 measured by the BP device 100
and accumulatively stored in the PI memory area 284. The collected
BP values of the subject 12 contain the BP values obtained by the
BP device 100 in the current operation cycle and the BP values
obtained by the BP device 100 in the prior operation cycles. The
CPU 62 supplies sound signals to the speaker drive circuit 278 to
drive the speaker 40 and thereby issue the selected one evaluation
comment.
The memory device 280 further includes an output-image (OI) memory
area 286 in which are pre-stored a plurality of sets of
evaluation-image data each of which is representative of a
corresponding one of a plurality of predetermined BP evaluation
pictorial images relating to the blood pressure of the subject 12,
or the time change of the BP values accumulatively stored in the PI
memory area 284. The CPU 62 selects, according to the control
programs pre-stored in the ROM 64, one of the stored evaluation
images which corresponds to the BP values of the subject 12
measured by a BP measuring device 100 in a current operation cycle,
and/or the collected BP values of the subject 12 measured by the BP
device 100 and accumulatively stored in the PI memory area 284. The
CPU 62 supplies print signals to the printer 26 to record the
selected one evaluation image on the recording sheet 292a, 292b,
292c.
The memory device 280 additionally includes an identification (ID)
data memory area 288 which stores one or more sets of ID data each
of which identifies a corresponding one of a plurality of living
subjects such as patients. The living subjects are registered in
the BP apparatus 208 by storing their ID data in the ID memory area
288. The memory device 280 has a subject-name (SN) memory area (not
shown) which stores a plurality of sets of subject-name data each
of which is representative of the name of a corresponding one of
the subjects. When a set of ID data is stored in the ID memory area
288, a set of subject-name data is stored in the SN memory area. If
the ID data read from a magnetic card 76 being inserted in a card
reader 74 are found to be identical with one of the sets of ID data
stored or registered in the ID memory area 288, the CPU 62 controls
the printer 26 to record, on the recording sheet 292a, 292b, 292c,
the name of a living subject corresponding to the read ID data,
together with the measured BP values obtained in the current
operation cycle and a graphic representation showing the time
change of the BP values accumulatively stored in the PI memory area
284.
The memory device 280 includes a medicine-related comment (MC)
memory area 290 in which are pre-stored a plurality of sets of
medicine-related comment data each of which is indicative of a
corresponding one of a plurality of predetermined medicine-related
comments relating to a plurality of medicines which may be
administered by doctors to the living subject 12. The BP apparatus
208 has a plurality of operable keys 272 respectively corresponding
to the plurality of medicines. When one of the operable keys 272 is
pushed by a doctor, the CPU 62 selects one of the medicine-related
comments stored in the MC memory area 290 and controls the printer
26 to record the selected one medicine-related comment, together
with the BP values and BP graph, on the recording sheet 292a, 292b,
292c.
The BP apparatus 208 has an image/comment edit device 273 which is
operable for inputting a command to the CPU 62 so that the CPU 62
controls the image reader 278 to read an original image and/or an
original comment recorded on an original sheet. The image reader
278 includes a display (not shown) for displaying the read original
image and/or comment. The edit device 273 is operable for editing
the original image and/or comment being displayed on the display.
The edit device 273 may include a cursor movable on the display,
and a mouse or keyboard operable for moving the cursor on the
display. The edit device 273 is capable of enlarging, reducing,
moving, and partly cutting out the original image and/or comment on
the display. The CPU 62 stores the image and/or comment edited by
the edit device 273, in the OI memory area 286 and/or the MC memory
area 290, respectively.
The BP apparatus 208 includes a random signal generator circuit 294
which generates a plurality of different random signals. The OI
memory area 286 is also capable of storing a plurality of random
selectable images which do not relate to the blood pressure of the
subject 12 and which correspond to the random signals produced by
the generator circuit 294. If a blood pressure measurement of the
subject 12 is carried out with the BP apparatus 208 being placed in
a random image select mode as one of selectable operation modes, as
a result of operation of a mode select dial (not shown) provided on
an operator panel 20, the CPU 62 selects one of the random
selectable images which corresponds to a random signal being
currently produced by the circuit 294, and records the thus random
selected one image together with the BP values and BP graph, on the
recording sheet 292a, 292b, 292c.
The BP apparatus 208 further includes a clock circuit 296 which
provides a time signal indicative of a current date and time. The
OI memory area 286 is also capable of storing a plurality of
time-related selectable images which do not relate to the blood
pressure of the subject and which are related to the time signals
produced from the clock circuit 296. If a blood pressure
measurement of the subject 12 is effected with the BP apparatus 208
being placed in a time-related image select mode established by
operating the mode select dial, the CPU 62 selects one of the
time-related selectable images which corresponds to a current date
and time provided by the clock circuit 296, and records the thus
selected one time-related image together with the BP values and BP
graph, on the recording sheet 292a, 292b, 292c.
In the second embodiment, the BP values measured by the BP
measuring device 100 are stored in the PI memory area 284 of the
memory device 280 each time a blood pressure measurement is carried
out on the subject 12. The OI memory area 286 stores different
evaluation images relating to the blood pressure of the subject 12;
a plurality of different groups of evaluation images (described
later); different images relating to the dates and times of
measurements provided by the clock circuit 296; and different
images corresponding to random signals or values provided by the
random signal generator circuit 294. The CPU 62 selects, from the
OI memory area 286, one of the evaluation images which corresponds
to the current BP values of the subject 12 measured by the BP
measuring device 100. The EC memory area 282 stores different
evaluation messages used for evaluating the BP values measured by
the device 100. The CPU 62 selects, from the EC memory area 282,
one of the evaluation comments which corresponds to the current BP
values measured by the device 100. The printer 26 records, on the
recording sheet 292a, 292b, 292c, the selected evaluation image and
the selected evaluation comment together with a list of the BP
values obtained by the device 100 in several BP measuring
operations and with a BP graph representing the time change of
those BP values.
The CPU 62 can select, from the OI memory area 286, one of the
different groups of evaluation images which is specified by the ID
data read from the magnetic card 76 being inserted in the card
reader 74. The CPU 62 can further select one of the selected group
of evaluation images which corresponds to the current BP values of
the subject 12, and control the printer 26 to record the thus
selected evaluation image together with the list of BP values and
the BP graph on the recording sheet 292a, 292b, 292c.
The medicine select keys 272 are selectively operable by doctors
for specifying and inputting one of different blood-pressure
control medicines which may be administered to patients. The MC
memory area 290 stores different comments related to the different
blood-pressure control medicines. While a medicine-related comment
output mode is selected on the BP apparatus 208, the CPU 62
selects, from the MC memory area 290, one of the medicine-related
comments which corresponds to the medicine input by a doctor
through operation of one of the select keys 272, and controls the
printer 26 to record the selected medicine-related comment together
with the BP values measured by the BP measuring device 100 on the
recording sheet 292a, 292b, 292c.
With a random image output mode being selected on the BP apparatus
208, the CPU 62 selects, from the OI memory area 286, one of the
random selectable images which corresponds to the random signal or
value provided by the random signal generator circuit 294, and
controls the printer 26 to record the thus random selected image
together with the BP values and the BP graph on the recording sheet
292a, 292b, 292c.
Similarly, with a time-related image output mode being selected on
the BP apparatus 208, the CPU 62 selects, from the OI memory area
286, one of the time-related selectable images which corresponds to
the time signal, i.e., current date and time, provided by the clock
circuit 296, and operates the printer 26 to record the selected one
time-related image together with the BP values and the BP graph on
the recording sheet 292a, 292b, 292c.
Furthermore, with an image edit mode being selected, the CPU 62
controls, in response to operation of the image edit device 273,
the image reader 278 to read in an original image from an original
and display the read-in original image on the display of the reader
278. Medical workers can edit the original image on the image
reader 278, by enlarging, reducing, and moving the image and
cutting out a part or parts of the image. Similarly, the medical
workers can edit an original comment that may be input to the image
reader 278 independently of an original image. The CPU 62 stores
the thus edited image and/or comment in the OI memory area 286
and/or the MC memory area 290, respectively.
There will be described the operation of the BP measuring apparatus
208.
FIG. 9 shows a flow chart representing a control program according
to which the BP apparatus 208 carries out a BP evaluation mode in
which the apparatus 208 outputs the measured, current BP values of
a living subject and an evaluation image and an evaluation comment
which evaluate the current BP values of the subject 12.
First, at Step SS1, the CPU 62 judges whether the operation of the
BP apparatus 208 has been started, by identifying whether a
magnetic card 76 has been inserted in a card insertion slot 28 of
the card reader 74, or a main switch (not shown) has been operated.
If a negative judgment is made at Step SS1, Step SS1 is repeated.
On the other hand, if a positive judgment is made, the control of
the CPU 62 proceeds with Step SS2 to control the card reader 74 to
read the ID data recorded on the ID card 76 being inserted in the
card slot 28. The CPU 62 temporarily stores, in the RAM 66, the ID
data read by the card reader 74.
Step SS2 is followed by Step SS3 to judge whether the set of ID
data read from the card 76 is identical with one of the sets ID
data stored or registered in the ID memory area 288. If a negative
judgment is made at Step SS3, the control of the CPU 62 goes to
Step SS4 where the set of ID data is stored or registered in the ID
memory area 288 according to an ID data register routine. Step SS4
is followed by Step SS5. On the other hand, if a positive judgment
is made, the control of the CPU 62 directly proceeds with Step SS5
to judge whether a START switch 22 has been operated to start a BP
measurement.
The CPU 62 repeats Step SS5 until a positive judgment is made at
this step. If a positive judgment is made at Step SS5, the control
goes to Step SS6, i.e., BP measure subroutine in which a systolic
(SAP), a diastolic (DAP), a mean blood pressure (MAP) value, and a
pulse rate (PR) value, of the living subject 12 are measured or
determined. In the BP measure subroutine, the CPU 62 operates,
according to a pre-stored algorithm, for automatically raising the
cuff pressure of an inflatable cuff 16 and determining during the
reduction of the cuff pressure the SAP, DAP, and MAP values of the
living subject 12 in to the known oscillometric BP measuring
method. For example, the SAP value may be determined as being equal
to a cuff pressure at the time of occurrence of a first maximum
difference out of the differences obtained by successively
calculating the difference of respective amplitudes of each pair of
successive pulses of the pulse wave signal SM supplied during the
reduction of the cuff pressure. Similarly, the DAP value may be
determined as being equal to a cuff pressure at the time of
occurrence of a second maximum difference out of those differences.
The MAP value is determined as being equal to a cuff pressure at
the time of occurrence of a pulse having a maximum amplitude out of
the pulses. The PR value is determined based on a time difference
between two successive pulses of the pulse wave signal SM.
Step SS6 is followed by Step SS7 to store, in the PI memory area
284, data indicative of the BP and PR values determined at Step
SS6, together with data indicative of the date and time provided by
the clock circuit 296, in relation with the ID data obtained at
Step SS2. Additionally, the CPU 62 commands the SAP, DAP, and PR
displays 32, 34, 36 to display the measured SAP, DAP, and PR
values, respectively.
At the following Step SS8, the CPU 62 selects, from the OI memory
area 286, one of the evaluation images which corresponds to the
current BP values measured at Step SS6 and selects, from the EC
memory area 282, one of the evaluation comments which corresponds
to the current BP values measured at Step SS6.
Step SS8 is followed by Step SS9 where the CPU 62 controls the
printer 26 to record or print, on the recording sheet 292 (292a,
292b, 292c) shown in FIG. 10, 11, or 12, (a) a name 232 of the
subject 12 corresponding to the ID data read from the card 76; (b)
a date and time when the current BP measurement is carried out; (c)
current BP values 236 (236a, 236b, 236c) measured at Step SS6; (d)
a current PR value 238 measured at Step SS6; (e) a list 240 of the
BP values and PR values accumulatively stored in the PI memory area
284; (f) a graphic representation 242 (242a, 242b, 242c) of the BP
values accumulatively stored in the PI memory area 284; (g) a
graphic representation 244 of the PR values accumulatively stored
in the PI memory area 284; (h) a pictorial evaluation image 246
(246a, 246b, 246c) corresponding to the current BP values; and (i)
an evaluation comment 248 (248a, 248b, 248c) corresponding to the
current BP values. FIG. 10 shows an example of an output by the BP
apparatus 208 for normal BP values; FIG. 11 shows an example of an
output for somewhat abnormal BP values; and FIG. 12 shows an
example of an output for abnormal BP values. The evaluation image
and comment 146a, 148a indicate that the current BP values are
normal; the image and comment 246b, 248b indicate that the current
BP values are somewhat abnormal; and the image and comment 246c,
248c indicate that the current BP values are abnormal.
It emerges from the foregoing description that in the second
embodiment the CPU 62 selects, from the output image (OI) memory
area 286, one of the different evaluation images 246a, 246b, 246c
which corresponds to the current BP values of the living subject 12
measured by the BP measuring device 100 and controls the printer 26
to record, on the recording sheet 292a, 292b, 292c the selected
evaluation image 246a, 246b, 246c together with the list 240 of the
BP values measured in the prior measuring operations and the BP
graph 242 indicating the time change of the prior and current BP
values. Since the evaluation image 246a, 246b, 246c corresponding
to the current BP values is output together with the BP values
obtained in the past measuring operations, the living subject 12 or
medical workers can visually identify an abnormality of the current
BP values, and the subject 12 can remember the abnormal measurement
result for a long time.
In addition, in the second embodiment, the printer 26 records, on
the recording sheet 292a, 292b, or 292c shown in FIG. 10, 11, or
12, (a) the name 232 of the living subject 12; (b) the date and
time of the current measurement; (c) the current BP values 236a,
236b, 236c; (d) the current PR value 238; (e) the list 240 of the
prior BP and PR values; (f) the graphic representation 242a, 242b,
242c of the prior and current BP values; (g) the graphic
representation 244 of the prior and current PR values; (h) the
evaluation image 246a, 246b, 246c corresponding to the current BP
values; and (i) the evaluation comment 248a, 248b, 248c
corresponding to the current BP values. Since medical workers or
the living subject 12 can carry the recording sheet 292a, 292b,
292c, the BP apparatus 208 eliminates the burden of writing down
the BP and PR values displayed on the display panel 30 or keeping
those values in mind.
Furthermore, in the second embodiment, since the BP graph 242a,
242b, 242c representing the time change of the prior and current BP
values obtained in the several BP measurements is output on the
recording sheet 292a, 292b, 292c, medical workers or the living
subject 12 can easily recognize the history of the BP values of the
subject 12.
While the BP apparatus 208 is placed in an evaluation-image change
mode as a result of operation of the mode select dial (not shown),
the apparatus 208 or CPU 62 operates according to a control program
represented by the flow chart of FIG. 13 and obtained by adding
Step SS71 between Steps SS7 and SS8 of the flow chart of FIG. 9. As
described previously, the output image (OI) memory area 286 stores
a plurality of groups of evaluation images. Since a normal (or
abnormal) BP range changes depending upon sex, age, patient's
medical history, etc., it is not appropriate to use a single group
of evaluation images to all the human beings including male and
female, young and old, health and sick, etc. Therefore, a plurality
of different groups of evaluation images are employed for male,
female, and old, respectively. The ID data recorded on the magnetic
card 72 include the data indicative of the sex, age, medical
history, etc. of the living subject 12 carrying the card 72, and
the CPU 62 selects, at Step SS71, one of the different groups of
evaluation images which one group corresponds the ID data read from
the card 72 at Step SS2. At Step SS8, the CPU 62 selects one of the
selected group of evaluation images which one image corresponds to
the current BP values of the subject 12 measured by the measuring
device 100. In this mode, the BP apparatus 208 outputs an
evaluation image more accurately evaluating the current BP values
of the male or female, young or old subject 12. Each image
belonging to the group of evaluation images for, e.g., the male may
contain the figure of a male person only. It may be the case with
the group of images for the female or the old. In those cases, if
an evaluation image indicating an abnormal blood pressure is output
on a recording sheet, the output image will give a clearer visual
impression to the subject 12.
While the BP apparatus 208 is placed in a medicine-related comment
output node in response to operation of the mode select dial, the
apparatus 208 or CPU 62 operates according to a control program
represented by the flow chart of FIG. 14 and obtained by adding
Step SS91 after Step SS9 of the flow chart of FIG. 9. As described
previously, the medicine-related comment (MC) memory area 290
stores a plurality of medicine-related comments relating to the
medicines which may be administered by doctors to patients. At Step
SS91, the CPU 62 selects, from the MC memory area 290, one of the
medicine-related comments which corresponds to the medicine
selected by a medical worker by pushing a corresponding one of the
medicine select keys 272, and controls the printer 26 to record,
e.g., on the recording sheet 292c shown in FIG. 12, the selected
medicine-related comment in addition to the other items 232-248.
For example, a medicine-related comment may read as follows: THIS
MEDICINE, NAMED "XXXX", IS FOR IMPROVING YOUR BLOOD PRESSURE. TAKE
"Y" TABLETS AFTER EVERY MEAL FOR "Z" DAYS. In the case where a
doctor makes a diagnosis based on the measured BP values of the
living subject 12 and hands out a selected blood pressure treating
medicine to the subject 12, the BP apparatus 208 outputs, in
response to doctor's input of data indicating the selected medicine
through operation of a corresponding key 272, a comment related to
the selected medicine together with the BP values on the recording
sheet 92. The medicine-related comment may describe the manner of
use of the medicine, the virtue of the medicine, directions for use
of the medicine, etc. Since the medicine-related comment is
recorded on the sheet 92, the doctor need not write down the
comment on a sheet of paper or the subject 12 need not keep it in
mind.
While the BP apparatus 208 is placed in the random image output
mode, or the time-related image output mode, in response to
operation of the mode select dial, the apparatus 208 or CPU 62
operates according to a control program represented by the flow
chart of FIG. 15 and obtained by adding Step SS82 in place of Step
SS8 of the flow chart of FIG. 9. As described previously, the OI
memory area 286 stores a plurality of random selectable images that
are not be related to blood pressure, and a plurality of
time-related selectable images that are not be related to blood
pressure. In the random image output mode, at Step SS82, the CPU 62
selects, from the OI memory area 286, one of the random selectable
images which corresponds to the random signal or value provided by
the random signal generator circuit 294 and controls, at Step SS9,
the printer 26 to record, on the recording sheet 292, the random
selected image in place of the evaluation image and message 246,
248 and in addition to the other items 232-244. In the time-related
image output mode, at Step SS82, the CPU 62 selects, from the OI
memory area 286, one of the time-related selectable images which
corresponds to the date and time provided by the clock circuit 294
and controls, at Step SS9, the printer 26 to record, on the
recording sheet 292, the selected time-related image in place of
the evaluation image and message 246, 248 and in addition to the
other items 232-244. The random or time-related selectable images
may include images representing season's flowers, season's
landscapes, etc. Those selectable images effectively operate for
visually impressing the measured BP values on the subject 12.
While the BP apparatus 208 is placed in the image/comment input and
edit mode in response to operation of the mode select dial, the
apparatus 208 or CPU 62 operates according to a control program
represented by the flow chart of FIG. 16. The routine of FIG. 16 is
carried out for preparing various images to be stored in the OI
memory area 286 and evaluation comments to be stored in the
evaluation comment (EC) memory area 282. First, at Step SB1, the
CPU 62 judges whether an original image has been read in from an
original upon operation of a reading-in key of the edit device 273.
If a negative judgment is made at Step SB1, Step SB1 is repeated.
On the other hand, if a positive judgment is made, the control of
the CPU 62 goes to Step SB2 to control the image reader 278 to read
in the original image from the original, e.g., sheet bearing the
original image. The original image may be an original evaluation
comment. Usually, an original evaluation comment is recorded on a
different or separate sheet from a sheet on which an original
pictorial image is recorded. At the following Step SB3, the CPU 62
edits the original image in response to command signals input
through operation of the edit device 273. Specifically, the CPU 62
enlarges or reduces the size of the original image, moves the
image, or cuts out a part of the image, on the display of the image
reader 278, so that the thus edited image is suitable for being
output on the recording sheet 92. Step SB3 is followed by Step SB4
to judge whether the editing operation has been finished, by
identifying whether an edit end key of the edit device 273 has been
operated. If a negative judgment is made at Step SB4, the control
of the CPU 62 returns to Step SB1 and the following steps. On the
other hand, if a positive judgment is made at Step SB4, the control
goes to Step SB5 to store the edited pictorial image in the OI
memory area 286, and store the edited evaluation comment in the EC
memory area 282, with or without relation with data specifying the
attributes of the edited image or comment. The attributes of an
edited image or comment may comprise (a) correspondence to the
normal or abnormal BP values, (b) correspondence to a specific
group for the male, female, young, or old, and (c) correspondence
to a specific time such as a season or a month. In this mode, the
BP apparatus 208 enables medical workers or other users to easily
input and edit, and then register, in the apparatus 208, their
desirable pictorial images and/or evaluation comments to be output
with measured BP values on a recording sheet 92.
It is to be understood that the BP apparatus 208 may otherwise be
modified.
For example, while the control circuit 56 or CPU 62 is capable of
carrying out all the control programs represented by the flow
charts of FIGS. 9, 13, 14, 15, and 16, the CPU 62 may be modified
to carry out one or more (but not all) of those programs.
While the memory device 280 is incorporated in the BP apparatus
208, it is possible to provide the memory device 280 outside the BP
apparatus 208 and connect the memory device 280 to the BP apparatus
208. Otherwise, the memory device 280 may be provided in a host
computer to which the BP apparatus 208 is connected via a
communication line such as a telephone line.
Next, there will be described a third embodiment of the present
invention. The third embodiment relates a blood pressure (BP)
measuring apparatus 310 having a side view and a front view shown
in FIGS. 17 and 18, respectively. The BP measuring apparatus 310 is
similar to the BP measuring apparatus 8 shown in FIGS. 1 and 2.
Therefore, the same reference numerals as used in FIGS. 1 and 2 are
used to designate corresponding elements or parts of the BP
apparatus 310, and the description of those elements or parts is
omitted. The following description will be focused on the
differences of the BP apparatus 310 from the BP apparatus 8.
The BP apparatus 310 has an automatic cuff winding device 330,
shown in FIG. 18, which automatically winds an inflatable cuff 16
(and an elongate belt 18) around an upper arm of a living subject
12 (FIG. 1). For carrying out a BP measurement using the BP
apparatus 310, the subject 12 is required to insert his or her arm
into an arm receiver 14 in the same manner as that used on the BP
apparatus 8 of FIG. 1. More specifically, the subject 12 inserts
his or her arm in the receiver 14 such that the elbow of the arm
comes out of a rear-side opening of the tunnel-like arm receiver
14. In the present embodiment, the cuff winding device 330 includes
the arm receiver 14, cuff 16, belt 18, and other elements
(described later); the cuff 16 serves as an inflatable bag; and the
belt 18 serves as a bag support. The cuff 16 and the belt 18
cooperate with each other to provide an arm belt for pressing the
subject's arm.
In FIG. 17, the BP apparatus 310 is placed on a table 338. A first
and a second microswitch 340, 342 are provided at a top and a
bottom of a front-side opening of the tunnel-like arm receiver 14.
Each of the two microswitches 340, 342 has a contact member 340a,
342a and is embedded in an inner surface 343 of a housing 10 such
that the contact member 340a, 342a is exposed to an inner space of
the arm receiver 14. When the subject's arm 12 is inserted in the
receiver 14 and appropriately positioned relative to the receiver
14, the respective contact members 340a, 342a of the two
microswitches 340, 342 do not contact the upper arm 12 so that each
contact member 340a, 342a takes its original state and each
microswitch 340,342 takes its OFF state. Each microswitch 340, 342
supplies a detection or non-detection signal indicative of its ON
or OFF state, to a control device 368 (FIG. 18). Thus, the
microswitches 340, 342 serve as a detector for identifying whether
the longitudinal axis line of the subject's upper arm 12 is aligned
with the longitudinal axis line of the cylindrical arm receiver
14.
At the rear opening of the arm receiver 14, there is provided an
elbow rest 344 having a curved surface shown in FIG. 17. The elbow
rest 344 is fixed to the housing 10 with a fixing member (not
shown). A third microswitch 346 is embedded in the curved surface
of the elbow rest 344 such that a contact member 346a of the
microswitch 346 is exposed in the curved surface. When the elbow of
the subject's arm 12 is placed on the elbow rest 344, the contact
member 346a of the switch 346 contacts the elbow and is pushed.
Consequently, the third switch 346 is changed from its OFF state to
its ON state and supplies the detection signal indicative of the ON
state to the control device 368. Thus, the third microswitch 346
identifies whether a sufficient length of the subject's arm 12 has
been inserted into the arm receiver 14.
As shown in FIG. 18, the BP apparatus 310 has, near the front end
thereof, a left and a right adjustable legs 348, 348 which extend
downward from a bottom wall 10a of the housing 12. The length of
extension of the legs 348 from the outer surface of the bottom wall
10a is adjustable in a manner described later. When the length of
extension of the legs 348 is adjusted, the angle of inclination of
the housing 10, therefore also the arm receiver 14, is changed
relative to the table 338.
Each leg 348 fits in a first cylinder 352 fixed to the inner
surface of the bottom wall 10a using a metal member 350, such that
each leg 348 is advanceable outward from the corresponding first
cylinder 352. The amount of advancement of the legs 348 from the
first cylinders 352, i.e., length of extension of the legs 348 from
the bottom wall 10a is adjusted by a cylinder drive device 354
provided in the housing 10. As shown in FIG. 19, the cylinder drive
device 354 includes a second cylinder 358 having a working fluid in
a fluid chamber 356; a piston 362 movable in the second cylinder
358 in an axial direction of the cylinder 358 and fixed to a rack
360; a motor 366 having a reduction gear unit and a rotation shaft
which supports a pinion 364 engaged with the rack 360.
The motor 366 with the reduction gear unit is driven or rotated in
response to a command from the control device 368, so that an
appropriate fraction of the working fluid is supplied via piping
370 from the fluid chamber 356 of the second cylinder 358 to a
fluid chamber 372 of the first cylinder 352, or so that an
appropriate fraction of the working fluid is removed via the piping
370 from the fluid chamber 372 of the first cylinder 352 into the
fluid chamber 356 of the second cylinder 358. Each leg 348 is fixed
to a piston 374 provided in the corresponding first cylinder 352.
When the amount of working fluid in the fluid chamber 372 is
increased or decreased and therefore the piston 374 is moved
forward or backward in the first cylinder 352, the amount of
advancement of each leg 348 from the corresponding first cylinder
352 is adjusted. Since the two first cylinders 352, 352 are
connected via the piping 370 and a bypass passage 376 to the
cylinder drive device 354, the single drive device 354 operates for
simultaneously adjusting the advancement amounts of the two legs
348, 348.
The control device 368 starts to adjust the angle of inclination of
the housing 10 or arm receiver 14, in response to the detection or
non-detection signal supplied from the third microswitch 346. The
control device 368 continues to adjust the inclination angle of the
housing 10 so long as at least one of the first and second
microswitches 340, 342 continues to supply the detection signal
indicative of the ON state to the control device 368, i.e., so long
as the subject's arm 12 continues to contact at least one of the
top and bottom of the front opening of the arm receiver 14. In the
present embodiment, the adjustable legs 348, first cylinders 352,
and cylinder drive device 354 cooperate with each other to serve as
an arm-receiver positioning device. The control device 368 may be
constituted by a microcomputer.
When the BP apparatus 310 is used to carry out a BP measurement on
the subject 12, a START switch 22 is operated, and then the subject
inserts his or her arm 12 into the arm receiver 14 from the front
opening thereof and places the elbow of the arm 12 on the elbow
rest 344. If a sufficient length of the arm 12 is inserted into the
receiver 14 and the third microswitch 346 provided in the elbow
rest 344 is placed in the ON state, the control device 368 starts
to adjust the inclination angle of the housing 10. If, in this
situation, the first or second microswitch 340, 342 is placed in
the ON state as a result of contact of the contact member 340a,
342a with the arm 12, the control device 368 controls the motor 366
to operate or rotate so that the working fluid is supplied to, or
removed from, the fluid chambers 372 of the first cylinders 352.
Thus, the amount of advancement of the legs 348 is adjusted. In the
case where the first microswitch 340 is pushed by the arm 12, the
motor 366 is rotated in a counterclockwise direction as seen in
FIG. 19, so that the legs 348 are advanced. On the other hand, in
the case where the second microswitch 342 is pushed by the arm 12,
the motor 366 is rotated in a clockwise direction as seen in FIG.
19, so that the legs 348 are retracted. When the control device 368
does not receive any detection signal from the two microswitches
340, 342 as a result of the adjusting operation, the control device
368 stops the operation of the cylinder drive device 354 and starts
to tight up the belt 18 and inflate the cuff 16 by supplying a
pressurized air to the cuff 16. Thus, a BP measurement is started.
Since the tightening up of the belt 18 and the inflation of the
cuff 16 wound around the subject's upper arm 12, and the BP
measuring method using the cuff 16 are well known in the art, the
description of those steps is omitted. Following completion of the
BP measurement, the cuff 16 is deflated and the belt 18 is
loosened, thereby permitting the subject to withdraw his or her arm
12 from the arm receiver 14. Thus, a series of steps are ended.
Once a BP measurement has been started, the control device 368 does
not operate the cylinder drive device 354 again before the elbow of
the arm 12 is lifted up and the contact member 346a of the third
microswitch 346 is restored to the OFF state thereof. Since the
motor 366 is provided with the reduction gear unit, the amount of
advancement of the legs 348 cannot be changed with the motor 366
being stopped.
It emerges from the foregoing description of the the third
embodiment that when the arm 12 is inserted in the arm receiver 14
and the elbow of the arm 12 is placed on the elbow rest 344, the
control device 368 controls the cylinder drive device 354 to adjust
the amount of advancement of the legs 348 so that each of the first
and second microswitches 340, 342 supplies a non-detection signal
indicative of the OFF state in which the corresponding contact
member 340a, 342a is not held in contact with the arm 12. Stated
differently, the control device 368 controls the cylinder drive
device 354 to adjust the angle of inclination of the arm receiver
14 relative to the table 338 so that the longitudinal axis line of
the upper arm 12 is substantially aligned with the longitudinal
axis line (i.e., central axis line) of the arm receiver 14. Thus,
the present BP apparatus 310 establishes an appropriate position of
the arm receiver 14 relative to the subject's arm 12 where the
arteries of the arm 12 are not locally or partially pressed by the
cuff 16, without requiring the subject to adjust his or her arm 12
relative to the receiver 14. Stated differently, the BP apparatus
310 accurately measures the BP values of the subject 12 while
permitting the subject 12 to take a natural posture.
Since in the present embodiment the control device 368 starts to
adjust the inclination angle of the arm receiver 14 when the
contact member 346a of the third microswitch 346 is pushed under
the elbow of the subject's arm 12 and starts a BP measurement
following completion of the adjusting of the inclination angle, the
BP apparatus 310 carries out the BP measurement with the arm 12
being appropriately inserted in the arm receiver 14.
FIG. 20 shows another arm-receiver positioning device 377 which may
be employed, in place of the legs 348, cylinders 352, and drive
device 354 shown in FIG. 18, for adjusting the inclination angle of
the housing 10 of the BP apparatus 310 relative to the table 338.
The positioning device 377 includes two legs 380, 380 each of which
includes an externally threaded axis portion 378; an internally
threaded nut 382 held in threaded engagement with the axis portion
378 of each leg 380 and having teeth in an outer circumferential
surface thereof; and a motor 388 having a rotation shaft 386 which
supports a pinion 384 held in engagement with the teeth of the nut
382. A fixing metal member 390 having a hole (not shown) through
which the axis portion 378 of each leg 380 extends, holds the
corresponding nut 382 such that the nut 382 cannot be moved in an
axial direction of the axis portion 378 of the leg 380. Each
adjustable leg 380 has an axial groove 392 formed in the threaded
outer surface of the axial portion 378. Since the metal member 390
has a key (not shown) extending into the hole through which the
axial portion 378 extends, and held in engagement with the axial
groove 392 of the axial portion 378. Consequently, each leg 380 is
prevented from being rotated about the axis thereof, and is
permitted to displace in the axial direction thereof with rotation
of the corresponding nut 382. The motor 388 is fixed with a fixing
metal member 394 to the inner surface of the bottom wall of the
housing 10, and operates or rotates in response to a command from
the control device 368. The two legs 388 are associated with the
corresponding motors 388, respectively. The arm-receiver
positioning device 377 may be made more compact than the
positioning device constituted by the legs 348, cylinders 352, and
drive device 354 shown in FIG. 18. The motors 388 need not be
provided with a reduction gear unit unlike the motor 366 shown in
FIG. 19.
FIGS. 21(A) and 21(B) show another detector 395 which may be
employed, in place of the microswitches 340, 342 shown in FIG. 18,
for identifying whether the longitudinal axis line of the upper arm
12 is substantially aligned with the longitudinal axis line of the
arm receiver 14. The detector 395 includes a number of air chambers
396 provided on the bottom of the inner surface 343 of the
tunnel-like arm receiver 14. In the present embodiment, the air
chamber 396 includes twelve air chambers 396a to 396l, i.e. first
array of air chambers 396a to 396f and second array of air chambers
396g to 396l. Each array 396a-396f, 396g-396l extends parallel to
the longitudinal axis line of the arm receiver 14. The air chambers
396h to 396l are not shown in FIG. 21(A) or 21(B) since those
chambers are provided in rear of the air chambers 396b to 396f
shown in FIG. 21(B). The twelve air chambers 396a-396l communicate
with pressure switches 398a to 398l, respectively. When each air
chamber 396 is pressed, a pressure change is produced in the
corresponding pressure switch 398, which supplies a pressure signal
indicative of the detected pressure of each chamber 396, to the
control device 368. When the subject's arm 12 is inserted into the
arm receiver 14 for a BP measurement, the control device 368 starts
to adjust the inclination angle of the housing 10, based on the
pressure signals supplied from the pressure switches 398a-398l, so
that the longitudinal axis line of the upper arm 12 is
substantially aligned with the longitudinal axis line of the arm
receiver 14. In the case where an angle, .theta., of the
longitudinal axis line, A, of the upper arm 12 from the
longitudinal axis line, .smallcircle., of the arm receiver 14 is
positive as shown in FIG. 21(b) (it is assumed that any angle of
rotation in a counterclockwise direction from the reference axis
.smallcircle. is positive), the respective pressures in the air
chambers 396e, 396f, 396k, 396l provided in the rear portion of the
arm receiver 14 are increased. Accordingly, the control device 368
operates for increasing the inclination angle of the housing 10 and
thereby decreasing the respective pressures of those chambers 396e,
396f, 396k, 396l. On the other hand, in the case where the angle
.theta. of the axis line A of the upper arm 12 from the axis line
.smallcircle. of the arm receiver 14 is negative, the respective
pressures in the air chambers 396a, 396b, 396g, 396h provided in
the front portion of the receiver 14 are increased. Accordingly,
the control device 368 operates for decreasing the inclination
angle of the housing 10 and thereby decreasing the respective
pressures of those chambers 396a, 396b, 396g, 396h. That is, the
control device 368 operates for positioning the housing 10 or arm
receiver 14 so that the pressing forces exerted by the upper arm 12
to the air chambers 396a to 396l are made substantially uniform
with one another. Consequently, the axis line A of the upper arm 12
is substantially aligned with the axis line .smallcircle. of the
arm receiver 14.
FIG. 22 shows another arm-receiver positioning device 399 which may
be employed for adjusting the height of the housing 10 of the BP
apparatus 310 from the table 338. The present positioning device
399 includes four adjustable legs 348 or 380 provided at the four
corners of the bottom wall of the housing 10. The control device
368 adjusts the respective amounts of advancement of the four legs
348, 380 from the bottom of the housing 10, all in the same manner
using the positioning device 348, 352, 354 shown in FIG. 18, or the
positioning device 377 shown in FIG. 20, in such a manner that the
inclination angle of the housing 10 relative to the table 2338 is
not adjusted but the height of the housing 10 from the table 338 is
adjusted. In FIG. 22, the first and second microswitches 340, 342
or the air chambers 396 and pressure switches 398 are not provided
on the inner surface 343 of the arm receiver 14, but an optical
sensor 402 which measures the sitting height of a living subject
400 or the height of the subject's shoulder, is provided on the top
of the outer circumferential surface of the arm receiver 14.
When the subject 400 sits in front of the BP apparatus 310 and
inserts his or her arm 12 into the arm receiver 14 for a BP
measurement, the control device 368 starts to measure, using the
sensor 402, the sitting height or shoulder's height of the subject
400. Based on the measured height, the control device 368 operates
to adjust the height of the housing 10 so that the longitudinal
axis line of the upper arm 12 is substantially aligned with the
longitudinal axis line of the arm receiver 14. Assuming that the
inclination angle of the arm receiver 14 is constant and the length
of the upper arm 12 (i.e. length between the elbow and the
shoulder) is constant, the control device 368 can determine, based
on the measured sitting or shoulder height of the subject 400, an
appropriate height of the housing 10 which ensures that the
longitudinal axis line of the upper arm 12 is aligned with the
longitudinal axis line of the arm receiver 14. Data or a map
representing a prescribed relationship between the sitting (or
shoulder's) heights of the subject 400 and the heights of the
housing 10 are/is pre-stored in a read only memory (ROM) provided
in the control device 368. The control device 368 determines, based
on a measured sitting or shoulder's height of the subject 400, a
desirable height of the housing 10 according to the prescribed
relationship. In the arm-receiver positioning device 399, the
sensor 402 indirectly measures the amount of misalignment of the
longitudinal axis line of the upper arm 12 from the longitudinal
axis line of the receiver 14.
It is to be understood that the BP apparatus 310 may be modified in
various manners.
For example, while the BP apparatus 310 adjusts the inclination
angle or height of the housing 10 as a whole, it is possible to
provide an automatic cuff winding device including the arm receiver
14, cuff 16, belt 18, etc., outside the housing 10, and place the
winding device on the housing 10. Alternatively, it is possible to
provide an automatic cuff winding device, separately from the
housing 10, and place the winding device on the table 338. In the
latter cases, the BP apparatus 310 may be adapted to adjust the
inclination angle of only the winding device relative to the
housing 10 or table 338, or the height of only the winding device
from the housing 10 or table 338.
Although the detector 395 shown in FIGS. 21(A), 21(B) includes
twelve air chambers 396, it is possible to employ a different
number of air chambers 396. For example, the detector 395 may
include only the four air chambers 396a, 396g, 396f, 396l provided
at the front and rear ends of the arm receiver 14. The detector 395
essentially needs at least one air chamber 396 at the front and
rear ends of the receiver 14, respectively, i.e., at least two air
chambers 396 in total.
In the BP apparatus 310 shown in FIG. 22, it is possible to replace
the sensor 402 with the microswitches 340, 342 or the air chambers
396 and pressure switches 398. On the contrary, in the BP apparatus
shown in FIGS. 17-20 or the BP apparatus shown in FIGS. 21(A) and
21(B), it is possible to replace the microswitches 340, 342 or the
air chambers 396 and pressure switches 398, with the sensor 402.
The sensors 340, 342, 396, 398, 402 may be replaced with other
sorts of pressure sensors which detect the pressing of the
subject's arm 12.
Although in FIG. 22 the BP apparatus 310 adjusts the height of the
housing 10, the apparatus 310 may further include a device for
adjusting the height of the table 338 on which the apparatus 310 is
placed. In the latter case, the height of the housing 10 can be
adjusted.
While the BP apparatus 31C has the detector 340, 342, 396, 398, 402
for detecting a misalignment of the upper arm 12 from the arm
receiver 14, only in a vertical plane, and adjusts the vertical
misalignment of the upper arm 12, it is possible that the BP
apparatus 310 have a horizontal misalignment detector for detecting
a misalignment of the upper arm 12 or the arm receiver 14 in a
horizontal plane, and a horizontal adjusting device for adjusting
the horizontal misalignment of the upper arm 12 or the arm receiver
14. The horizontal misalignment detector may include microswitches
provided at the left and right ends of the inner surface 343 of the
receiver 14. The horizontal adjusting device may include a device
for rotating the housing 10 as a whole, or the automatic cuff
winding device 14, 16, 18, about a vertical axis line extending
through the elbow rest 344 and perpendicular to the tale 338. In
the latter case, the subject is not required to adjust his or her
arm 12 relative to the arm receiver 14, also in the horizontal
plane.
In the BP apparatus 310, it is possible to omit the third
microswitch 346. In the latter case, however, the BP apparatus 310
needs a start key operable for commanding the control device 368 to
start, after insertion of the arm 12 into the arm receiver 14,
adjusting the position of the receiver 14.
The arm-receiver positioning device 348, 352, 354 shown in FIG. 18,
device 377 shown in FIG. 20, or device 399 shown in FIG. 22 may be
replaced by other sorts of positioning devices; such as a gear
device which includes adjustable legs 348 or 380 each having an
axial portion with teeth, i.e., rack portion, a pinion engaged with
the rack portion of each leg, and a motor with a reduction gear
unit which operates for directly advancing and retracting each leg
from and into the housing 10.
Referring next to FIG. 23, there is shown a blood pressure (BP)
monitor apparatus 500 as a fourth embodiment of the present
invention.
In FIG. 23, reference numeral 510 designates an inflatable cuff
adapted to be wound around a body portion (e.g., upper arm) of a
living subject (e.g., patient) so as to press the upper arm. The
cuff 510 includes an inflatable bag 510a formed of an elastic sheet
(e.g., rubber sheet or vinyl sheet), and an inextensible arm belt
510b in which the bag 510a is accommodated. The bag 510a of the
cuff 510 is connected via piping 518 to a pressure sensor 512, an
air pump 514, and a pressure regulator valve 516.
The pressure sensor 512 includes, e.g., a semiconductor pressure
sensing element (not shown) which detects an air pressure in the
cuff 510 ("cuff pressure") and supplies a detection signal, SP, to
a low-pass filter 520, a first band-pass filter 522, and a second
band-pass filter 523. The low-pass filter 520 permits only a DC
(direct current) or static-pressure component of the detection
signal SP to pass therethrough, thereby supplying a cuff-pressure
signal, SK, representing the detected static cuff pressure,
P.sub.c, to an analog-to-digital (A/D) converter 524.
The first band-pass filter 522 permits only a 1 to 10 Hz frequency
AC (alternating current) component of the detection signal SP to
pass therethrough, thereby supplying a first pulse-wave signal,
SM1, representing a pulse wave of the subject, to the A/D converter
524. The pulse wave is produced in the cuff 510 because of the
pulsation of arteries of the upper arm under the cuff 510 in
synchronism with the heartbeats of the subject, while the cuff
pressure P.sub.c is changed within an appropriate pressure range.
Thus, the pulse wave produced in the cuff 510 is obtained as the AC
component of the detection signal SP supplied from the pressure
sensor 512.
The second band-pass filter 523 permits only a 0.5 to 20 Hz
frequency AC component of the detection signal SP to pass
therethrough, thereby supplying a second pulse-wave signal, SM2, to
the A/C converter 524. The first band-pass filter 522 has a narrow
frequency range (e.g., 1 to 10 Hz) for obtaining, from the
detection signal SP, successive pulse amplitudes free from artifact
noise possibly mixed therewith because of physical motion of the
subject. Pulse amplitudes are pressure oscillations produced in the
cuff 510 in synchronism with the heartbeats of the subject while
the cuff pressure P.sub.c is slowly changed at a rate of, e.g., 2
to 3 mmHg/sec in measuring a blood pressure (BP) value of the
subject. On the other hand, the second band-pass filter 523 has a
comparatively wide frequency range (e.g., 0.5 to 20 Hz) for
obtaining, from the same signal SP, a pulse wave having a waveform
similar to that of a pulse wave which is directly or invasively
obtained from inside an artery of the subject. The second band-pass
filter 523 is used to obtain the waveform of a pulse wave while the
cuff pressure P.sub.c is held at a prescribed value (described
later). The A/D converter 524 has a time division multiplexer for
time sharing of the three analog signals SK, SM1, SM2, and
concurrently converts those analog signals to respective digital
signals. In the present embodiment, the first and second band-pass
filters 522, 523 serve as a pulse wave detector.
The present BP monitor apparatus 500 has an arithmetic control
device 526 which is essentially constituted by a microcomputer
including a CPU 528, a RAM 530, a ROM 532, a first output interface
534, and a second output interface 536. The CPU 528 receives the
three digital signals SK, SM1, SM2 from the A/D converter 524, and
processes those signals by utilizing the temporary-storage function
of the RAM 530 and the control programs pre-stored in the ROM 532,
so that the CPU 528 controls the operations of the air pump 514 and
the regulator valve 516 via the first output interface 534 and
controls an output device 538 via the second output interface 536.
The output device 538 includes an image display panel (e.g.,
liquid-crystal panel) which has a number of picture elements and is
capable of displaying numerals and curves representing the measured
BP values and the detected pulse-wave waveform of the subject. The
output device 538 may further include a printer, as needed, which
records using an ink numerals and curves on a recording sheet.
A mode switch 540 is manually operable for selecting one of a
single-BP-measurement mode and a BP-monitor mode. The mode switch
540 selectively supplies one of a first signal indicative of the
single-measurement mode and a second signal indicative of the
monitor mode, to the CPU 528. An ON/OFF switch 542 is manually
operable for starting and stopping the present BP monitor apparatus
500, and alternatively supplies a START signal and a STOP signal to
the CPU 528 upon operation thereof.
Thus, the BP monitor apparatus 500 includes a pulse wave detector
(i.e., first and second band-pass filters 522, 523) for detecting,
as a pulse wave, a pressure oscillation produced in the cuff 510
wound around a body portion of a living subject, in synchronism
with the heartbeats of the subject, while the cuff 510 presses the
subject's body portion. The BP monitor apparatus 500 also includes
a BP measuring device 508 which determines a BP value of the
subject based on the change of pulse amplitudes, A.sub.m, which are
obtained as the cuff pressure P.sub.c is changed. The BP measuring
device 508 includes the elements 510, 512, 514, 516, 518, 520, 522,
523, and 526. The control device 526 or CPU 528 controls the
pressure regular valve 516 for repetitively changing and holding
the cuff pressure Pc to and at a prescribed pressure value lower
than a mean BP value of the subject (hereinafter, this period is
referred to as the "operative period"), in each non-BP-measuring
period, T.sub.2M (FIG. 27), in which the BP measuring device 508
does not operate for a BP measurement. A prescribed non-operative
period, T.sub.1M, is inserted between two successive operation
periods. The CPU 528 operates for determining a rate of change,
.theta.(=.DELTA.A.sub.m /.DELTA.P.sub.c), of the pulse amplitudes
A.sub.m with respect to the cuff pressure P.sub.c. The CPU 528 also
operates for identifying, based on the determined rate of change
.theta., whether the subject is suffering an abnormal blood
pressure.
In the case where the subject has a normal blood pressure, the BP
monitor apparatus 500 obtains successive pulse amplitudes whose
envelope is shown at solid line in FIG. 29. This envelope has an
angle, .alpha., approximating a rate of change .theta. thereof
corresponding to a certain cuff pressure P.sub.c-1. On the other
hand, in the case where the subject is suffering an abnormally low
blood pressure, the monitor apparatus 500 obtains successive pulse
amplitudes whose envelope is shown at one-dot chain line in FIG.
29. This envelope has an angle, .beta., approximating a rate of
change .theta. thereof corresponding to the same cuff pressure
P.sub.c-1. The angle .beta. is significantly greater than the angle
.alpha., because the respective values of the one-dot-chain-line
envelope are slightly smaller than those of the solid-line envelope
and simultaneously the upper peak of the former envelope
corresponds to a lower cuff pressure than a lower cuff pressure to
which the upper peak of the latter envelope corresponds. In view of
this fact, the control device 526 or CPU 528 judges that the
subject is suffering an abnormally low blood pressure, if the rate
of change .theta. exceeds a reference value, .theta..sub.o.
However, if the subject is in the state of shock, the BP apparatus
500 provides successive pulse amplitudes whose envelope is shown at
two-dot chain line in FIG. 29. This envelope has an angle, .gamma.,
approximating a rate of change .theta. thereof corresponding to the
same cuff pressure P.sub.c-1. The angle .gamma. is smaller than the
angle .alpha.. However, the respective values of the
two-dot-chain-line envelope are significantly smaller than those of
the solid-line envelope. Therefore, the CPU 328 further judges
whether a detected pulse amplitude is smaller than a reference
amplitude, Am.sub.o, and if a positive result or judgment is made
the CPU 328 identifies that the subject is suffering an abnormally
low blood pressure. When the CPU 528 makes a judgment that the
subject has an abnormal blood pressure, the BP measuring device 508
automatically measures a BP value of the subject according to a
control program pre-stored in the ROM 532.
The pressure regulator valve 516 is controlled to change the cuff
pressure P.sub.c from atmospheric pressure to a prescribed pressure
level, P.sub.CH, so that the first band-pass filter 522 detects a
plurality of pulses having different amplitudes A.sub.m and the CPU
528 determines, based on the detected pulse amplitudes A.sub.m, a
rate of change .theta. of the pulse amplitudes A.sub.m with respect
to the cuff pressure P.sub.c. Thereafter, the regulator valve 516
is controlled to hold the cuff pressure P.sub.c at the prescribed
pressure P.sub.CH for a prescribed pressure-hold period, T.sub.3M,
so that the band-pass filter 522 detects a pulse wave, or
respective pulses of the pulse wave, which are to be utilized for
other purposes described below in short and later in detail.
The control device 526 or CPU 528 further judges whether the blood
pressure of the subject is abnormal, based on a pulse magnitude
A.sub.m detected in a pressure-hold period T.sub.3M, in a manner
described later. When the CPU 528 makes a positive judgment in this
manner, the BP measuring device 508 immediately starts to carry out
a BP measurement on the subject. Thus, whenever the control device
526 or CPU 528 judges that the subject is suffering an abnormal
blood pressure, the BP measuring device 508 measures a BP value of
the subject.
In FIG. 23, reference numeral 546 designates an reference-value
input device which is manually operable to input or specify the
reference values which are to be used by the control device 526 or
CPU 528 in judging whether the subject is suffering an abnormal
blood pressure. The control device 526 or CPU 528 further functions
to change the prescribed pressure value P.sub.CH, based on the
reference values input through the input device 546. When the
control device 526 or CPU 528 judges that the subject is suffering
an abnormal blood pressure, the output device 538 displays that
judgment on the image-display panel thereof.
There will be described the operation of the BP monitor apparatus
500 constructed as described above, by reference to the flow charts
of FIGS. 24 and 25. Initially, at Step S101, the CPU 528 judges
whether the START/STOP switch 542 has been operated for starting
the operation of the present apparatus 500, based on the START or
STOP signal supplied from the switch 542. If a negative judgment is
made at Step S101, the control of the CPU 528 waits for receiving
the START signal from the switch 542. Meanwhile, if a positive
judgment is made, the control proceeds with Step S102 to operate
the air pump 514 and the pressure regulator valve 516 so as to
supply a pressurized air to the inflatable cuff 510 (i.e., bag
510a) and thereby quickly increase the air pressure in the cuff
510, i.e., cuff pressure Pc.
Step S102 is followed by Step S103 to judge whether the cuff
pressure P.sub.c has reached a prescribed target pressure, P.sub.CM
(e.g., 180 mmHg). If a negative judgment is made at Step S103, the
CPU 528 repeats Steps S102 and S103. Meanwhile, if a positive
judgment is made, the control of the CPU 528 proceeds with Step
S104 to stop the air pump 514 and change the degree of opening of
the pressure regulator valve 516 so as to slowly deflate the cuff
510, i.e., reduce the cuff pressure P.sub.c. This slow cuff
deflation is effected at a rate of, e.g., 2 to 3 mmHg/sec suitable
for BP measurements. Step S104 is followed by Step S105 to judge
whether the CPU 528 has received a length of first pulse wave
signal SM1 corresponding to one pulse having an amplitude, i.e.,
one cycle of heartbeat of the subject. If a negative judgment is
made at Step S1O5, the CPU 528 repeats Steps S104 and S105.
Meanwhile, if a positive judgment is made at Step S105, the control
of the CPU 528 proceeds with Step S106 to operate according to a
known oscillometric BP measurement algorithm, i.e., determine the
BP values of the subject. Step S106 is followed by Step S107 to
judge whether the BP measurement subroutine at Step S106 has been
completed. While the cuff pressure P.sub.c is slowly reduced in the
BP measuring period, the respective amplitudes of successive pulses
of the pulse wave, i.e., pulse wave signal SM1 initially increase
and then decrease as shown in FIG. 28. The amplitude of one pulse
("pulse amplitude") is obtained by subtracting the lower-peak
magnitude of the one-pulse signal SM1 from the upper-peak of the
same. In the known oscillometric BP measurement algorithm, a cuff
pressure P.sub.c at the time when the pulse amplitudes
significantly greatly increase is determined as a systolic BP
value, P.sub.sys, of the subject; a cuff pressure P.sub.c at the
time of detection of the greatest pulse amplitude is determined as
a mean BP value, P.sub.mean ; and a cuff pressure P.sub.c at the
time when the pulse amplitudes significantly greatly decrease is
determined as a diastolic BP value, P.sub.dia.
If a negative judgment is made at Step S107, the CPU 528 repeats
Steps S104 through S107. Meanwhile, if a positive judgment is made
at Step S107, the control of the CPU 528 proceeds with Step S108 to
store the three BP values P.sub.sys, P.sub.mean, P.sub.dia in the
RAM 530 and display those BP values in digits on the image-display
panel of the output device 538. At the following Step S109, the CPU
528 fully opens the pressure regulator valve 516 so as to quickly
deflate the cuff 510, i.e., quickly decrease the cuff pressure
P.sub.c and thereby release the subject's upper arm from the cuff
pressure P.sub.c. In the present embodiment, Steps S102 to S109
serve as a part of the BP measuring device 508 that automatically
carries out a BP measurement in a series of prescribed steps.
Step S109 is followed by Step S110 to determine a relationship
between BP values, P.sub.BP, and pulse amplitudes A.sub.m which
relationship is utilized at Step S124 described later.
Specifically, the CPU 528 determines a first P.sub.BP -A.sub.m
relationship based on the BP value P.sub.sys and the pulse
amplitude A.sub.m corresponding to the cuff pressure P.sub.c
determined as the BP value P.sub.sys, and a second P.sub.BP
-A.sub.m relationship based on the BP value P.sub.dia and the pulse
amplitude A.sub.m corresponding to the cuff pressure P.sub.c
determined as the BP value P.sub.dia. The first or second P.sub.BP
-A.sub.m relationship may be defined by the following linear
expression: P.sub.BP =K.sub.1 .times.A.sub.m +K.sub.2, where
K.sub.1 and K.sub.2 are constants, as shown in FIG. 26. This linear
expression defines a P.sub.BP -A.sub.m relationship proper to the
specific living subject. The constant K.sub.2 may be a prescribed
value, or zero.
At the following Step S111, the CPU 528 judges whether the BP
monitor apparatus 500 is currently placed in the BP-monitor mode,
based on a mode signal supplied from the mode switch 540. If a
negative judgment is made at Step S111, that is, if the apparatus
500 is currently placed in the single-BP-measurement mode, the
current control cycle of the CPU 528 in accordance with this main
routine is ended, and the control of the CPU 528 returns to Step
S101 and the following steps. On the other hand, if a positive
judgment is made at Step S111, that is, if the apparatus 500 is
currently placed in the BP-monitor mode, the control of the CPU 528
goes to Step S112 and the following steps, i.e., BP monitor
subroutine. The CPU 528 repeats Steps S113 through S128 at a
prescribed period of time, T.sub.1M (e.g., 1 to 3 minutes).
At Steps S112 and S113, the CPU 528 clears the contents of a second
and a first time counter (i.e., timers) T2 and T1, respectively.
Step S113 is followed by Step S114 to increment the contents of the
two timers T1, T2 each by one, i.e., T1.rarw.T1+1 and T2.rarw.T2+1.
At the following Step S115, the CPU 528 judges whether the contents
of the first timer T1 has reached the prescribed time period
T.sub.1M. Each time the first timer T1 counts up the reference time
T.sub.1M, the CPU 528 controls the air pump 514 and the regulator
valve 516 to increase the cuff pressure P.sub.c up to the hold
pressure P.sub.CH so as to monitor the blood pressure of the
subject.
Shortly after the beginning of the BP monitor operation, negative
judgments are made at Step S115, so that the CPU 528 repeats Steps
S114 and S115. Meanwhile, if a positive judgment is made at Step
S115, the control of the CPU 528 proceeds with Step S116 to operate
the air pump 514 and the regulator valve 516 to slowly increase the
cuff pressure P.sub.c. The rate of increasing of the cuff pressure
P.sub.c is pre-determined at, e.g., 3 mmHg/sec so that the BP
monitor apparatus 500 can obtain at least three pulses before the
cuff pressure P.sub.c is raised up to the hold pressure
P.sub.CH.
Step S116 is followed by Step S117 to detect each pulse which
occurs during the slow increasing of the cuff pressure P.sub.c and
store the amplitude A.sub.m of each detected pulse in an
appropriate area of the RAM 530. In addition, the CPU 528
determines a straight line approximating the detected at least
three pulse amplitudes A.sub.m. As shown in FIG. 28, this straight
line fits to a low-pressure-side portion of the envelope of the
subject's pulse amplitudes A.sub.m obtained in the BP measuring
period at Step S106. On the approximation line, the CPU 528
determines a rate of change .theta.(=.DELTA.A.sub.m
/.DELTA.P.sub.c) of the pulse amplitudes A.sub.m with respect to
the cuff pressure P.sub.c, based on prescribed cuff pressure values
P.sub.c-1 and P.sub.c-2, according to the following expression
(1):
where A.sub.m1 and A.sub.m2 are respective pulse amplitudes
corresponding to the cuff pressure values P.sub.c-1, P.sub.c-2 on
the approximation line.
In the present embodiment, Step S117 and a portion of the control
device 526 for carrying out this step cooperate with each other to
serve as means for determining a rate of change of pulse amplitudes
A.sub.m with respect to cuff pressure P.sub.c.
Step S117 is followed by Step S118 to judge whether the determined
rate of change .theta. is greater than a reference value
.theta..sub.0. The reference value .theta..sub.0 corresponds to the
angle .beta. obtained on the low-pressure-side portion of the
envelope (indicated at one-dot-chain line in FIG. 29) of the pulse
amplitudes of a living subject suffering abnormally low blood
pressure values, e.g., 90 mmHg systolic BP value and 50 mmHg
diastolic BP value. If a positive judgment is made at Step S118,
the control of the CPU 528 goes to Step S119 to operate the output
device 438 to indicate that the subject's blood pressure is
abnormal. Following Step S119, the control of the CPU 528 returns
to Step S102 and the following steps to immediately measure a BP
value of the subject at the time of identification of the subject's
BP abnormality.
On the other hand, if a negative judgment is made at Step S118, the
control of the CPU 528 goes to Step S120 to judge whether each
pulse amplitude A.sub.m is greater than a reference value A.sub.m0.
The reference value A.sub.m0 corresponds to the angle .gamma.
obtained on the low-pressure-side portion of the envelope
(indicated at two-dot-chain line in FIG. 29) of the pulse
amplitudes of a living subject who is currently in the state of
shock. If a negative judgment is made at Step S120, the control of
the CPU 528 goes to Step S119 to control the output device 438 to
indicate that the subject is in the state of shock. Following Step
S119, the control of the CPU 528 returns to Step S102 and the
following steps to immediately measure a BP value of the subject at
the time of identification of the subject's shock state. In the
present embodiment, Steps S118 and S120 and a portion of the
control device for carrying out these steps cooperate with each
other to serve as first abnormality judging means for identifying a
blood pressure abnormality of a living subject.
On the other hand, if a positive judgment is made at Step S120, the
control of the CPU 528 goes to Step S121 to judge whether the cuff
pressure P.sub.c has reached the prescribed hold pressure P.sub.CH.
The hold pressure P.sub.CH is pre-determined to fall within a range
of 20 to 30 mmHg which is adequately lower than the mean BP value
P.sub.mean of the subject and which ensures that the BP monitor
apparatus 500 detects a time change of the pulse amplitudes
A.sub.m. If a negative judgment is made at Step S121, the control
of the CPU 528 goes back to Step S116 and the following steps.
Meanwhile, if a positive judgment is made, the control goes to Step
S122 to stop the slow increasing of the cuff pressure P.sub.c and
temporarily hold the cuff pressure P.sub.c at the hold pressure
P.sub.CH for the prescribed pressure-hold period T.sub.3M, for
example, 2 seconds.
Step S122 is followed by Step S123 to read in a pulse A.sub.mh
detected while the cuff pressure P.sub.c is held at the hold
pressure P.sub.CH. At the following Step S124, the CPU 528
estimates a systolic and a diastolic BP value, P.sub.sysE and
P.sub.diaE, of the subject, based on the read-in pulse amplitude
A.sub.mh, according to the first and second PBP-Am relationships
determined at Step S110.
At the following Step S125, the CPU 528 judges whether the
estimated systolic BP value P.sub.sysE is smaller than a reference
value, P.sub.sysE0, or whether the estimated diastolic BP value
P.sub.diaE is smaller than a reference value, P.sub.diaE0. These
reference values P.sub.sysE0, P.sub.diaE0 are employed for
monitoring an abnormal decrease or fall of the blood pressure of
the subject, and are pre-determined at, e.g., 90 mmHg and 50 mmHg,
respectively. If a positive judgment is made with respect to at
least one of the two questions at Step S125, the control of the CPU
528 goes to Step S126 to operate the output device 538 to indicate
an abnormal decrease of the subject's blood pressure. Then, the
control of the CPU 528 returns to Step S102 and the following steps
to measure a BP value of the subject at the time of detection of
the abnormal BP decrease.
On the other hand, if a negative judgement is made with respect to
both the two questions of Step S125, the control of the CPU 528
goes to Step S127 to deflate the cuff 510, i.e., reduce the cuff
pressure P.sub.c to atmospheric pressure, thereby releasing the
subject's upper arm from the pressing of the cuff 510 held at the
hold pressure P.sub.CH. Step S127 is followed by Step S128 to judge
whether the contents of the second timer T2 has reached a
prescribed reference value T.sub.2M. This reference value T.sub.2M
is a regular interval of time at which the control device 526
periodically carries out Steps S102 and the following steps, and is
pre-selected at a time of 10 to 30 minutes. Shortly after the
beginning of the BP monitor operation, negative judgments are made
at Step S128, so that the CPU 528 carries out Steps S113 and the
following steps. Meanwhile, if a positive judgment is made at Step
S128, the control of the CPU 528 goes back to Step S102 and the
following steps.
When the BP monitor apparatus 500 is operated according to the flow
charts of FIGS. 24 and 25, the cuff pressure P.sub.c changes as
shown in FIG. 27. In the BP monitor period, i.e., non-BP-measuring
period following the BP-measuring period effected in response to
the starting operation of the ON/OFF switch 540, the CPU 528
periodically operates for slowly increasing the cuff pressure
P.sub.c up to the prescribed hold pressure P.sub.CH, while
alternately inserting the prescribed interval time T.sub.1M between
successive two pressure-hold periods T.sub.3M. The CPU 528
determines a rate of change .theta. of the pulse amplitudes A.sub.m
obtained during the slow increasing of the cuff pressure P.sub.c,
and judges, based on the determined rate of change .theta., whether
the subject is suffering an abnormally low blood pressure. In
addition, the CPU 528 judges whether the subject is suffering an
abnormal blood pressure decrease or fall because of being in the
state of shock. Furthermore, the CPU 528 estimates, based on the
pulse amplitude A.sub.mh detected during the pressure-hold period
T.sub.3M, the systolic and diastolic BP values P.sub.sysE,
P.sub.diaE and judges whether the subject is suffering an
abnormally low blood pressure, based on the estimated BP values
P.sub.sysE, P.sub.diaE.
It emerges from the foregoing description that in the fourth
embodiment, the CPU 528 determines a rate of change .theta. of the
pulse amplitudes A.sub.m with respect to the cuff pressure P.sub.c,
each time the CPU 528 operates the air pump 514 and regulator valve
516 to slowly increase, following a prescribed interval T.sub.1M,
the cuff pressure P.sub.c from atmospheric pressure to the
prescribed pressure P.sub.CH lower than the mean BP value
P.sub.mean of a living subject. The CPU 528 judges, based on the
determined rate of change .theta., whether the subject is suffering
a blood pressure abnormality. Thus, in the present embodiment, the
BP monitor apparatus 500 utilizes, for monitoring the blood
pressure of the subject, the phenomenon that the rate of change
.theta. of the low-pressure-side portion of the envelope
representing the change of the pulse amplitudes A.sub.m with
respect to the cuff pressure P.sub.c, changes as the blood pressure
of the subject changes. Therefore, the BP monitoring of the
apparatus 500 is carried out with high reliability. Since the rate
of change .theta. is determined based on the data obtained while
the cuff pressure P.sub.c is changed in a low pressure range from
atmospheric pressure to the hold pressure P.sub.CH, the BP monitor
operation of the apparatus 500 does not cause the subject to feel
discomfort due to the pressing of the inflated cuff 510.
Furthermore, the BP measuring device 508 automatically measures BP
values of the subject in a series of prescribed steps, each time
the control device 526 or CPU 528 identifies that the subject is
suffering a blood pressure abnormality. Thus, the BP measuring
device 528 reliably measures the BP values of the subject
immediately after the identification of the blood pressure
abnormality. The thus obtained BP values of the subject ensure that
medical workers such as doctors make appropriate treatments with
the subject.
When a living subject is in a shock state, the envelope
representing the change of the pulse amplitude A.sub.m with respect
to the cuff pressure P.sub.c, becomes more or less flat. Therefore,
in this case, it is very difficult for the BP apparatus 500 to make
an abnormality judgment based on the rate of change .theta. of the
pulse amplitude A.sub.m with respect to the cuff pressure P.sub.c.
However, the CPU 528 also judges whether the pulse amplitude
A.sub.m detected during the slow increasing of the cuff pressure
P.sub.c is smaller than the reference value A.sub.m0. If the pulse
amplitude A.sub.m is smaller than the reference value A.sub.m0, the
CPU 528 judges that the subject is suffering an abnormal blood
pressure fall, thereby easily identifying that the subject is in
the state of shock.
In the BP monitor apparatus 500, the control device 526 or CPU 528
controls the air pump 514 and the pressure regulator valve 516 to
change the cuff pressure P.sub.c to the prescribed hold pressure
P.sub.CH and then hold the cuff pressure P.sub.c at the pressure
level P.sub.CH for the prescribed period T.sub.3M. Based on the
pulse amplitude A.sub.mh obtained during the pressure-hold period
T.sub.3M, the CPU 528 finds the subject's blood pressure
abnormality. Therefore, the BP monitoring of the present apparatus
500 is carried out with high reliability.
Thus, in the present embodiment, whenever the control device 526 or
CPU 528 finds a blood pressure abnormality of a living subject, the
BP measuring device 508 automatically measures BP values of the
subject. Therefore, the reliability of the BP monitoring of the
apparatus 500 is improved as such.
It is to be understood that the BP monitor apparatus 500 may be
modified in various ways.
For example, FIG. 30 shows a flow chart representing steps which
may be carried out in place of Step S117 of FIG. 25 by the control
device 526 or CPU 528. The steps of FIG. 30 serve as a subroutine
for determining a rate of change .theta. of pulse amplitudes
A.sub.m.
At Step S117-1, the CPU 528 controls the air pump 514 and the
regulator valve 516 to hold the cuff pressure P.sub.c at a first
hold pressure P.sub.CH1. The first hold pressure P.sub.CH1 is
pre-selected at a value which ensures that the monitor apparatus
500 obtains pulse amplitudes A.sub.m suitable for determining a
rate of change .theta. of the pulse amplitudes A.sub.m on the
low-pressure-side portion of the envelope of the pulse amplitudes
A.sub.m shown in FIG. 28, and may be pre-determined to fall within
a range of 15 to 20 mmHg. Step S117-1 is followed by Step S117-2 to
judge whether the respective amplitudes of two successive pulses
are substantially equal to each other. This step is provided for
the purpose of discarding noise. Since the cuff pressure P.sub.c is
not changed at Step S117-2 (and also at Step S117-5 (described
later)), the CPU 528 reads in the second pulse wave signal SM2 that
has been filtered through the second band-pass filter 523 and is
more accurate than the first pulse wave signal SM1. If a negative
judgment is made at Step S117-2, the CPU 528 repeats Steps S117-1
and S117-2. On the other hand, if a positive judgment is made at
Step S117-2, the control of the CPU 528 proceeds with Step S117-3
to store, as a first pulse amplitude, A.sub.m1, the two pulse
amplitudes substantially equal to each other, in the RAM 530.
At the following Step S117-4, the CPU 528 controls the air pump 514
and the regulator valve 516 to increase and hold the cuff pressure
P.sub.c to and at a second hold pressure P.sub.CH2. The second hold
pressure P.sub.CH2 is pre-selected at a value which ensures that
the monitor apparatus 500 obtains pulse amplitudes A.sub.m greater
than the pulse amplitude Am1 stored at Step S117-3 and suitable for
determining the rate of change .theta. on the low-pressure-side
portion of the envelope of the pulse amplitudes A.sub.m shown in
FIG. 28, and may be pre-determined to fall within a range of 25 to
30 mmHg. Step S117-4 is followed by Step S117-5 to judge whether
the respective amplitudes of two successive pulses are
substantially equal to each other. If a negative judgment is made
at Step S117-2, the CPU 528 repeats Steps S117-4 and S117-5. On the
other hand, if a positive judgment is made at Step S117-5, the
control proceeds with Step S117-6 to store, as a second pulse
amplitude, A.sub.m2, the two pulse amplitudes substantially equal
to each other, in the RAM 530.
At the following Step S117-7, the CPU 528 calculates the rate of
change .theta. from the first and second hold pressure values
P.sub.CH1, P.sub.CH2 and the first and second pulse amplitude
values A.sub.m1, A.sub.m2, according to the following expression
(2):
FIG. 31 shows a time change of cuff pressure P.sub.c when the
monitor apparatus 500 operates according to the flow chart of FIG.
30. Specifically described, the cuff pressure P.sub.c is stepwise
increased up to the first hold pressure P.sub.CH1, and the first
hold pressure P.sub.CH1 is maintained until two successive pulses
having equal amplitudes are obtained and the first pulse amplitude
A.sub.m1 is stored. Subsequently, the cuff pressure P.sub.c is
stepwise increased from the first hold pressure P.sub.CH1 to the
second hold pressure P.sub.CH2, and the second hold pressure
P.sub.CH2 is maintained until two successive pulses having equal
amplitudes are obtained and the second pulse amplitude A.sub.m2 is
stored. The second hold pressure P.sub.CH2 may be equal to the hold
pressure P.sub.CH used as a reference pressure value at Step S121
of FIG. 25. In the latter case, Steps S121 and S122 are omitted
from the flow chart of FIG. 25, and at Step S124 the CPU 528
estimates, based on the second pulse amplitude A.sub.m2, the
systolic and diastolic BP values P.sub.sysE, P.sub.diaE of the
subject.
This modified control manner enjoys the same advantages as those
with the control manner in accordance with the flow charts of FIGS.
24 and 25. Additionally, since the rate of change .theta. of the
low-pressure-side increasing portion of the pulse-amplitude
envelope is calculated based on the first and second pulse
amplitudes A.sub.m1, A.sub.m2 obtained at the prescribed first and
second hold pressures P.sub.CH1, P.sub.CH2, the calculated rate of
change .theta. enjoys a high accuracy and accordingly the accuracy
of monitoring of the present apparatus 500 is improved. Moreover,
since the apparatus 500 stores and utilizes the equal amplitude of
two successive pulses obtained at the prescribed cuff pressure
P.sub.CH1 or P.sub.CH2, noise which is possibly mixed with
heartbeat-synchronous pulses can effectively be removed or omitted,
so that the accuracy of monitoring of the apparatus 500 is more
improved. Furthermore, in the case where the second hold pressure
P.sub.CH2 is equal to the hold pressure P.sub.CH, the second pulse
amplitude Am.sub.2 may be used for identifying a subject's blood
pressure abnormality at Step S124 of FIG. 25. Thus, the
pressure-hold periods T.sub.3M and Steps S121 and S122 may be
omitted.
FIG. 32 shows a flow chart including steps which may be carried out
in addition to the steps of the flow charts of FIGS. 24 and 25 by
the monitor apparatus 500. According to this flow chart, the
control device 526 or CPU 528 changes the hold pressure P.sub.CH or
the second hold pressure P.sub.CH2 based on a reference value
.theta..sub.0, or reference value P.sub.sysE0 or P.sub.diaE0, which
is input through operation of the reference-value input device 546.
The input device 546 has three keys for inputting or specifying a
reference value .theta..sub.0, a reference value P.sub.sysE0, and a
reference value P.sub.diaE0, respectively, each of which is
selected by a medical worker such as a doctor. At Step SA101, the
CPU 528 reads in a reference value .theta..sub.0, P.sub.sysE0,
P.sub.diaE0 input through the input device 546, and updates the
prior reference value .theta..sub.0, P.sub.sysE0, P.sub.diaE0
stored in the RAM 530, by replacing the prior value with the newly
input value. Step SA101 is followed by Step SA102 to determine a
new hold pressure P.sub.CH or a new second hold pressure P.sub.CH2,
based on the new reference value .theta..sub.0, P.sub.sysE0,
P.sub.diaE0, according to a map shown in FIG. 33. This map defines
a prescribed relationship between reference value .theta..sub.0,
P.sub.sysE0, or P.sub.diaE0 and hold pressure P.sub.CH or
P.sub.CH2. Although only a single map is shown in FIG. 33, three
different maps are, in fact, used for respective relationships
between three sorts of reference values .theta..sub.0, P.sub.sysE0,
P.sub.diaE0 and hold pressure P.sub.CH (or second hold pressure
P.sub.CH2). In this modified control manner, Step SA102 and a
portion of the control device 526 for carrying out this step
cooperate with each other to serve as means for changing the hold
pressure P.sub.CH or second hold pressure P.sub.CH2. This modified
control manner enjoys the advantage that the hold pressure P.sub.CH
or second hold pressure P.sub.CH2 is made as low as possible and
accordingly the discomfort which the subject may feel due to the
cuff pressure P.sub.c in the BP monitor mode is minimized.
Although in the fourth embodiment the rate of change .theta. of
pulse amplitudes A.sub.m with respect to cuff pressure P.sub.c is
determined according to the expression (1) or (2), it is possible
to determine, as a rate of change .theta., a maximum rate of
change, (dA.sub.m /dP.sub.c).sub.max, of an increasing portion of
the pulse-amplitude envelope shown in FIG. 28 which portion is
defined as a portion from the smallest pulse amplitude (i.e., lower
peak) to the greatest pulse amplitude (i.e., upper peak).
While the BP monitor apparatus 500 holds the cuff pressure P.sub.c
at the hold pressure P.sub.CH in each pressure-hold period
T.sub.3M, it is possible to omit the pressure-hold periods
T.sub.3M. That is, the BP monitor apparatus 500 may be modified not
to operate for identifying a subject's blood pressure abnormality
based on a pulse amplitude obtained in each pressure-hold period
T.sub.3M.
In the case where the hold pressure P.sub.CH or the second hold
pressure P.sub.CH2 is pre-selected at a prescribed value, the
prescribed value is by no means limited to the exemplified pressure
range of 20 to 30 mmHg, but may be selected with some effect at any
value lower than a mean BP value P.sub.mean of a living subject.
The prescribed value may be selected at a value lower than a
diastolic BP value P.sub.dia of the subject, with more effect,
because the blood flow of the subject is not stopped under the cuff
pressure P.sub.c held at the selected value.
While the monitor apparatus 500 obtains a pulse wave, i.e.,
respective pulses of the pulse wave via the first or second
band-pass filter 522, 523 from the blood pressure cuff 510, it is
possible to employ another cuff or inflatable bag different from
the cuff 510 and detect a pulse wave as a pressure oscillation
produced in the different cuff or bag.
Referring next to FIG. 34, there is shown an automatic blood
pressure (BP) measuring apparatus 600 as a fifth embodiment of the
present invention. The BP measuring apparatus 600 has the function
of estimating a blood pressure value of a living subject.
The BP measuring apparatus 600 has a construction similar to that
of the BP monitor apparatus 500 shown in FIG. 23. Therefore, the
same reference numerals as used in FIG. 23 are used to designate
the corresponding elements or parts of the BP apparatus 600 shown
in FIG. 34, and the description of those elements or parts is
omitted. However, the BP apparatus 600 does not have the
reference-value input device 546, and has a RAM 630 having three
memory areas 644, 646, 680 (described later), in place of the RAM
530.
The BP measuring apparatus 500 includes a pressure sensor 512 and a
low-pass filter 520 which provide a static pressure in an
inflatable cuff 510 ("cuff pressure P.sub.c ") wound around a body
portion (e.g., upper arm) of a living subject; a BP measuring
device 508 which determines a BP value or values of the subject
based on the change of respective amplitudes of pulses of a pulse
wave as a pressure oscillation produced in the cuff 510 while the
cuff pressure P.sub.c is slowly decreased; and an electric air pump
514 and a pressure regulator valve 516 which are controlled to
start a BP measuring operation by quickly increasing the cuff
pressure P.sub.c up to a target pressure, P.sub.CM, and
subsequently slowly decreasing the same P.sub.c from the target
pressure P.sub.CM, and to reduce the cuff pressure P.sub.c down to
atmospheric pressure after a BP value or values of the subject has
or have been determined during the slow decreasing of the cuff
pressure P.sub.c. A first band-pass filter 522 provides a waveform
of a pulse of a pulse wave ("pulse waveform") produced in the cuff
510 while the cuff pressure P.sub.c is quickly increased. An
arithmetic and control device 526 or a CPU 528 thereof operates for
determining, based on (a) the pulse waveform provided by the
band-pass filter 523 during the BP measuring operation of the BP
measuring device 508 and (b) the BP value or values determined by
the BP measuring device 508, a relationship between pulse waveform,
cuff pressure P.sub.c, and blood pressure which relationship is
proper to the living subject. The control device 526 or CPU 528
additionally functions for estimating, according to the thus
determined relationship, a BP value or values of the subject, based
on (a) a pulse waveform actually supplied from the first band-pass
filter 522 and (b) a cuff pressure P.sub.c at the time of supplying
of the pulse waveform.
The waveform of one pulse of a pulse wave produced in the form of a
pressure oscillation in the cuff 510 in synchronism with one cycle
of heartbeat of a living subject, changes as the cuff pressure
P.sub.c changes from a value around a systolic BP value, P.sub.sys,
of the subject, to a value around a mean blood pressure P.sub.mean
of the same, and to a diastolic BP value, P.sub.dia, of the same.
FIGS. 35(A), 35(B), and 35(C) shows three waveforms of one pulse
obtained at three cuff pressure values P.sub.c generally
corresponding to systolic, mean, and diastolic BP values P.sub.sys,
P.sub.mean, P.sub.dia, respectively. As can be understood from the
three waveforms shown in FIGS. 35(A), 35(B), and 35(C), the
changing of a pulse waveform means that various characteristics of
the pulse waveform change. Those waveform characteristics include a
maximum slope of an increasing portion of the pulse waveform
obtained in a time period, T.sub.ds (FIG. 39); a height of a
primary peak of the pulse waveform, i.e., pulse amplitude; a
position and a shape of a secondary peak of the pulse waveform,
etc. Therefore, the CPU 528 determines in advance a relationship
between (a) evaluated values of a waveform characteristic, (b)
values of cuff pressure P.sub.c, and (c) values of blood pressure
and estimates, according to the relationship, a BP value of the
subject based on an evaluated value of a characteristic of a pulse
waveform actually supplied during the quick increasing of the cuff
pressure P.sub.c and a cuff pressure value P.sub.c at the time of
supplying of the pulse waveform.
In addition, the control device 526 or CPU 528 operates for
determining, based on an estimated BP value of the subject, a
target pressure value P.sub.CM to which the cuff pressure P.sub.c
is quickly increased for a BP measurement. The CPU 528 controls the
air pump 514 and the pressure regulator valve 516 to slowly
decrease the cuff pressure P.sub.c after the cuff pressure P.sub.c
has been raised up to the target pressure P.sub.CM. The CPU 528
also operates for identifying a subject's blood pressure
abnormality by comparing the estimated BP value with a reference
value. If the subject's abnormal blood pressure is identified, the
CPU 528 controls an output device 538 to indicate that the blood
pressure of the subject is abnormal.
Hereinafter, there will be described the operation of the BP
measuring apparatus 600 constructed as described above, by
reference to the flow charts of FIGS. 36 and 37. First, at Step
SA201, the CPU 528 judges whether a START/STOP switch 542 has been
operated for starting the operation of the present apparatus 600,
based on a START or a STOP signal supplied from the switch 542. If
a negative judgment is made at Step SA201, the control of the CPU
528 waits for receiving the START signal from the switch 542.
Meanwhile, if a positive judgment is made, the control proceeds
with Step SA202 to operate the air pump 514 and the regulator valve
516 so as to supply a pressurized air to the cuff 510 (i.e., bag
510a) and thereby quickly increase the air pressure in the cuff
510, i.e., cuff pressure P.sub.c at a rate of about 30 to 40
mmHg/sec.
Step SA202 is followed by Step SA203 to judge whether the cuff
pressure P.sub.c has reached an initial target pressure P.sub.CM
prescribed at, e.g., 180 mmHg. If a negative judgment is made at
Step SA203, the CPU 528 repeats Steps SA202 and SA203. Meanwhile,
if a positive judgment is made, the control of the CPU 528 proceeds
with Step SA204 to stop the air pump 514 and change the degree of
opening of the regulator valve 516 so as to slowly deflate the cuff
510, i.e., reduce the cuff pressure P.sub.c. This slow cuff
deflation is carried out at a rate of, e.g., 2 to 3 mmHg/sec
suitable for BP measurements. Step SA204 is followed by Step SA205
to judge whether the CPU 528 has received a length of first pulse
wave signal SM1 corresponding to one pulse, i.e., one cycle of
heartbeat of the subject. If a negative judgment is made at Step
SA205, the CPU 528 repeats Steps SA204 and SA205.
Meanwhile, if a positive judgment is made at Step SA205, the
control of the CPU 528 proceeds with Step SA206 to store, in a
waveform memory area 644 of the RAM 630, the waveform of the
one-pulse signal SM1 supplied from the first band-pass filter 522.
Step SA206 is followed by Step SA207 where the control device 526
or CPU 528 operates according to a known oscillometric BP
measurement algorithm, i.e., determine actual BP values of the
subject. Step SA207 is followed by Step SA208 to judge whether the
BP measurement subroutine at Step SA207 has been completed. While
the cuff pressure P.sub.c is slowly reduced, the respective
amplitudes of successive pulses of the pulse wave, i.e., pulse wave
signal SM1 initially increase and then decrease as shown in FIG.
38. In the known oscillometric BP measurement algorithm, a cuff
pressure P.sub.c at the time when the pulse amplitudes
significantly greatly increase is determined as a systolic BP
value, P.sub.sys, of the subject; a cuff pressure P.sub.c at the
time of detection of the greatest pulse amplitude is determined as
a mean BP value, P.sub.mean ; and a cuff pressure P.sub.c at the
time when the pulse amplitudes significantly greatly decrease is
determined as a diastolic BP value, P.sub.dia.
If a negative judgment is made at Step SA208, the CPU 528 repeats
Steps SA204 through SA208. Meanwhile, if a positive judgment is
made at Step SA208, the control of the CPU 528 proceeds with Step
SA209 to store the three BP values P.sub.sys, P.sub.mean, P.sub.dia
in a BP memory area 646 of the RAM 630 and display those BP values
in digits on an image-display panel of the output device 538. At
the following Step SA210, the CPU 528 fully opens the pressure
regulator valve 516 so as to quickly deflate the cuff 510, i.e.,
quickly decrease the cuff pressure P.sub.c down to atmospheric
pressure and thereby release the subject's upper arm from the cuff
pressure P.sub.c. In the present embodiment, Steps SA204 to SA208
serve as part of the BP measuring device 508 that automatically
carries out a BP measurement.
At the following Step SA211, the CPU 528 judges whether a flag,
F.sub.k, is currently set at one, i.e., F.sub.k =1. The state of
F.sub.k =1 indicates that a relationship used for estimating a BP
value of the subject has been determined. Upon initialization of
the present BP apparatus 600, the flag F.sub.k is reset to zero,
i.e., F.sub.k= 0. For a while following the starting of operation
of the BP apparatus 600, negative judgments are made at Step SA211,
and the control of the CPU 528 proceeds with Step SA212 to
determine, for the subject around an upper arm of whom the cuff 510
is wound, a relationship between (a) evaluated values of a waveform
characteristic, (b) values of cuff pressure P.sub.c, and (c) values
of blood pressure. Step SA212 is followed by Step SA213 to set the
flag F.sub.k to F.sub.k =1. Once the flag F.sub.k has been set to
F.sub.k =1 in a certain control cycle, a positive judgment is made
at Step SA211 in the next and following control cycles, so that the
control of the CPU 528 proceeds with Step SA214 by bypassing Steps
SA212 and SA213.
At Step SA212, the control device 526 or CPU 528 evaluates the
waveform of each of the respective pulses stored in the waveform
memory area 644 at Step SA206, with respect to each of various
waveform characteristics such as pulse amplitude, Amp-b; evaluated
value, SLOPE; evaluated value, %MAP; increasing-portion percentage,
%IPP; and peak index, PI. As shown in FIG. 39, the pulse amplitude
Amp-b of a pulse waveform is defined as the difference between the
upper and lower peaks of the pulse waveform (i.e., difference
obtained by subtracting the lower peak magnitude, DAP, from the
upper peak magnitude, SAP). That is, the pulse amplitude Amp-b
evaluates the height of the pulse waveform. The evaluated value
SLOPE is defined as the maximum differential, (dP/dt).sub.max, of
an increasing portion of a pulse waveform, i.e., the greatest slope
of the increasing portion of the waveform. The value %MAP is
defined as the percentage (=100.times.a/b) of the y coordinate
(i.e., height, a) of the barycentric coordinates of the area
bounded by a pulse waveform and a base line extending parallel to
the X axis (i.e., "time" axis) and passing through the lower peak,
DAP, of the pulse waveform, with respect to the pulse amplitude b
(Amp-b). The value %MAP evaluates the degree of sharpness of the
waveform. The increasing-portion percentage %IPP is defined as the
percentage (=100.times.T.sub.ds /T) of a time duration, T.sub.ds,
of the increasing portion of a pulse waveform with respect to a
cyclic period, T (sec), of the pulse waveform. The value %IPP
evaluates the degree of imbalance of the waveform. The peak index
PI is defined as the percentage (=100.times.T.sub.sh /T ) of a time
duration, T.sub.sh, between the upper peak, SAP, and the secondary
peak of a pulse waveform, with respect to the cyclic period T (sec)
of the pulse waveform. The evaluated value PI indicates the
position of the secondary peak on the pulse waveform.
At Step SA212, the CPU 528 obtains, from the evaluated values of
the waveform characteristics Amp-b, SLOPE, %MAP, %IPP, PI, data
representing a relationship between the measured BP values of the
subject and each waveform characteristic as shown in FIG. 40. Since
the BP values P.sub.sys, P.sub.mean, P.sub.dia of the subject are
measured by reading the cuff pressure values P.sub.c, the CPU 528
can determine a relationship between blood pressure BP, each
waveform characteristic Amp-b, SLOPE, %MAP, %IPP, PI, and cuff
pressure Pc as shown in FIGS. 41, 42, 43, 44, and 45 where the
blood pressure BP is variable as a parameter. Although only three
curves each representing a BP value are shown in each of FIGS.
41-45, a number of curves each representing a BP value are, in
fact, employed in each graph or map. Each map contains a number of
base curves given according to a prescribed rule, and those base
curves are modified based on a measured BP value of the subject
which may be one of the measured systolic, mean, and diastolic BP
value P.sub.sys, P.sub.mean, P.sub.dia.
Step SA213 is followed by Step S214 to judge whether the BP monitor
apparatus 600 is currently placed in the BP-monitor mode, based on
a mode signal supplied from a mode switch 540. If a negative
judgment is made at Step S214, that is, if the apparatus 600 is
currently placed in the single-BP-measurement mode, the current
control cycle in accordance with the main routine is ended, and the
control of the CPU 528 returns to Step SA201 and the following
steps. On the other hand, if a positive judgment is made at Step
SA214, that is, if the apparatus 500 is currently placed in the
BP-monitor mode, the control of the CPU 528 goes to Step SA215 to
clear the contents of a time counter (timer), T3, to zero and
subsequently to Step SA216 to judge whether the START/STOP switch
542 has been operated again, based on the START/STOP signal
supplied from the switch 542. If a positive judgment is made at
Step SA216, the current control cycle is ended, and the control of
the CPU 528 goes back to Step SA201.
On the other hand, if a negative judgment is made at Step SA216,
the control goes to Step SA217 to increment the contents of the
timer T3 by one, i.e., T3.rarw.T3+1. At the following Step SA217,
the CPU 528 judges whether the contents of the timer T3 has reached
a prescribed reference time T.sub.4M. This reference time T.sub.4M
is the period of cyclic measurements of the BP measuring apparatus
600, and is pre-selected to fall within a range of several minutes
to several tens of minutes. For a while following the beginning of
the BP monitor operation, negative judgments are made at Step
SA218, so that the CPU 528 repeats Steps SA216, SA217 and SA218.
Meanwhile, if a positive judgment is made at Step SA218, the
control of the CPU 528 proceeds with Step SA219 and the following
steps to estimate a BP value of the subject based on the waveform
of a pulse obtained in a quick inflation of the cuff 510.
More specifically described, at Step SA219, the CPU 528 operates,
like at Step SA202, the air pump 514 and the pressure regulator
valve 516 to quickly increase the cuff pressure P.sub.c. Step SA219
is followed by Step SA220 to judge whether a length of the pulse
wave signal SM1 corresponding to a cycle of heartbeat of the
subject, i.e., the waveform of one pulse is supplied to the control
device 526 or CPU 528. If a negative judgment is made at Step
SA220, the CPU 528 repeats Steps SA219 and SA220 to quickly
increase the cuff pressure P.sub.c. Meanwhile, if a positive
judgment is made, the control of the CPU 528 goes to Step SA221 to
store the waveform of the one-pulse signal SM1 in the waveform
memory area 644 of the RAM 630.
At the following Step SA222, i.e., BP estimation subroutine, the
CPU 528 estimates a BP value of the subject, based on the pulse
waveform stored in the memory 644 at Step SA221, according to the
various relationships determined at Step SA212 that are proper to
the subject around an upper arm of whom the cuff 510 is currently
wound. Specifically, at Step SA222, the CPU 528 calculates one or
more of characteristic evaluated values Amp-b, SLOPE, %MAP, %IPP,
PI of the stored waveform, and subsequently calculates one or more
BP values, based on the calculated one or more evaluated values
Amp-b, SLOPE, %MAP, %IPP, PI and a cuff pressure value P.sub.c at
the time of supplying of the pulse waveform, according to the
corresponding one or more of the relationships or maps shown in
FIGS. 41-45. The CPU 528 estimates a BP value of the subject, based
on the thus calculated one or more BP values, according to a
prescribed arithmetic expression.
As described above, the blood pressure BP employed as a parameter
in each of the relationships or maps of FIGS. 41-45 may be the
systolic, mean, or diastolic BP value P.sub.sys, P.sub.mean,
P.sub.dia of the subject. For example, in the case where the maps
of FIGS. 41-45 are determined for the systolic BP value P.sub.sys
of the subject, the CPU 528 estimates, at Step SA222, a systolic BP
value of the subject according to those maps. This applies to the
mean and diastolic BP values of the subject. Therefore, in the case
where the maps of FIGS. 41-45 are determined for each of the
systolic, mean and diastolic BP values P.sub.sys, P.sub.mean,
P.sub.dia of the subject, the CPU 528 estimates, at Step SA222, a
systolic, a mean and a diastolic BP value of the subject according
to those maps.
The CPU 528 determines, as an estimated BP value of the subject, an
average of the calculated two or more BP values. Otherwise, the CPU
528 may be modified to determine, as an estimated BP value, an
average of respective weighted values of the calculated two or more
BP values, or an average of one or more BP values obtained by
removing the greatest and smallest values from the three or more
calculated BP values. However, if the CPU 528 judges that the
stored waveform is abnormal, the CPU 528 does not estimate a BP
value of the subject. In this case, therefore, a negative judgment
is made at the following Step SA223. The CPU 528 judges whether the
stored waveform is abnormal, by identifying whether each of one or
more characteristic evaluated values Amp-b, SLOPE, %MAP, %IPP, PI
of the waveform falls within a corresponding normal range. In the
case where the first pulse, i.e., first waveform obtained during
the quick inflation of the cuff 510 is normal, the CPU 528
estimates, at Step SA222, a BP value of the subject based on the
first waveform. Accordingly, a positive judgment is made at Step
SA223.
Steps SA222 is followed by Step SA223 to judge whether a BP
estimation at Step SA222 has been completed. If a negative judgment
is made at Step SA223, the control of the CPU 528 goes back to Step
SA219 and the following steps to quickly increase the cuff pressure
P.sub.c. On the other hand, if a positive judgment is made, the
control goes to Step SA224 to judge whether the estimated BP value
of the subject is abnormal. For example, in the case of an
estimated systolic BP value, the CPU 528 judges whether the
estimated systolic BP value falls within a range of 100 to 200
mmHg; and in the case of an estimated diastolic BP value, the CPU
528 judges whether the estimated diastolic BP value falls within a
range of 50 to 150 mmHg. If a negative judgment is made, the CPU
528 judges that the estimated BP value is abnormal.
If a positive judgment is made at Step SA224, i.e., if the
estimated BP value is found to be abnormal, the control of the CPU
528 goes to Step SA225 to control the output device 538 to indicate
that the estimated BP value is abnormally high or low. On the other
hand, if a negative judgment is made at Step SA224, the control
goes to Step SA226 to determine a modified target pressure,
P.sub.CMR, such that the pressure P.sub.CMR is equal to an
estimated BP value of the subject. This estimated systolic BP value
may be equal to the estimated systolic BP value obtained at Step
SA222, or a systolic BP value estimated based on the mean or
diastolic BP value obtained at Step SA222. Step SA226 is followed
by Step SA227 to judge whether the cuff pressure P.sub.c has
reached a pressure value, P.sub.CMR +.alpha., obtained by adding a
prescribed buffer or excess value to the pressure P.sub.CMR. If a
negative judgment is made at Step SA227, the control of the CPU 528
goes back to Step SA219 and the following steps to quickly increase
the cuff pressure P.sub.c. On the other hand, if a positive
judgment is made, the control goes to Step SA204 and the following
steps to slowly decrease the cuff pressure P.sub.c and carry out a
BP measurement according to the oscillometric method.
As is apparent from the foregoing description, in the fifth
embodiment, Step SA212 and a portion of the control device 526 for
carrying out this step cooperate with each other to serve as means
for determining the relationships shown in FIGS. 41-45, and Step
SA222 and a portion of the control device 526 for carrying out this
step cooperate with each other to serve as means for estimating a
systolic, a mean or a diastolic BP value of the subject, based on
(a) each characteristic evaluated value of a pulse waveform
supplied from the first band-pass filter 522 during the quick
inflation of the cuff 510, and (b) a cuff pressure value P.sub.c at
the time of supplying of the pulse waveform, according to a
corresponding one of the relationships or maps of FIGS. 41-45. The
second pulse wave signal SM2 supplied from the second band-pass
filter 523 may be used in place of the first pulse wave signal SM1,
for supplying a pulse waveform to the control device 526 or CPU
528.
The present BP measuring apparatus 600 estimates a BP value of the
subject, based on (a) a characteristic evaluated value of a pulse
waveform supplied during a quick cuff inflation period before a
slow cuff deflation period, and (b) a cuff pressure value P.sub.c
at the time of supplying of the pulse waveform. Thus, the apparatus
600 provides a considerably accurate estimated BP value of the
subject shortly after the beginning of each of cyclic BP
measurements carried out in the BP-monitor mode.
In the case where, at Step SA222, two or more BP values of the
subject are calculated according to the two or more relationships
determined at Step SA212, the CPU 528 estimates a BP value of the
subject based on the two or more calculated BP values. Therefore,
the thus estimated BP value of the subject enjoys a high
accuracy.
Step SA226 and a portion of the control device 526 for carrying out
this step cooperate with each other to serve as means for
determining a modified target pressure P.sub.CMR based on an
estimated BP value of the subject provided at Step SA222; and the
pressure regulator valve 516 and a portion of the control device
526 for controlling the valve 516 cooperate with each other to
serve as means for regulating the cuff pressure P.sub.c by quickly
increasing the pressure P.sub.c up to a pressure higher by an
access .alpha. than the determined target pressure P.sub.CMR and
thereafter slowly decreasing the pressure P.sub.c. Since the
pressure higher by the access .alpha. than the determined target
pressure P.sub.CMR is a necessary and adequate pressure higher than
the estimated systolic BP value of the subject, the BP apparatus
600 effectively prevents the cuff pressure P.sub.c from being
increased up to an unnecessarily high value, thereby preventing the
subject from feeling discomfort due to the unnecessarily high
pressure.
Step SA224 and a portion of the control device 526 for carrying out
this step cooperate with each other to serve as judging means for
judging whether the blood pressure of the subject is abnormal, by
comparing the estimated BP value of the subject obtained at Step
SA222, with a reference pressure range. The output device 538 and a
portion of the control device 526 for controlling the output device
538 cooperate with each other to serve as means for outputting an
indication that the blood pressure of the subject is abnormal, when
the judging means makes a positive judgment. Therefore, the present
apparatus 600 ensures that medical workers can recognize a
subject's blood pressure abnormality at an early point of time in a
quick cuff inflation period. Accordingly, the medical workers such
as doctors can take appropriate medical actions on the subject.
It is to be understood that the BP measuring apparatus 600 as the
fifth embodiment may be modified in various ways.
For example, the BP apparatus 600 may be modified to operate
according to the control program represented by the flow charts of
FIGS. 46 and 47. In this modified manner of operation, the pressure
sensor 512 serves as a pressure detector which detects a cuff
pressure P.sub.c, i.e., pressing pressure of the cuff 510 wound
around a body portion of a living subject; the first or second
band-pass filter 522, 523 serves as a pulse wave detector which
detects, as a pulse wave, a pressure oscillation mixed with the
cuff pressure P.sub.c detected by the pressure sensor 512; the BP
measuring device 508 determines a BP value of the subject based on
the change of successive pulse amplitudes produced during the slow
decreasing of the cuff pressure P.sub.c ; the pressure regulator
valve 516 and a portion of the control device 526 for controlling
the valve 516 cooperate with each other to start a BP measurement
by quickly increasing the cuff pressure P.sub.c up to a prescribed
target pressure value P.sub.CM and subsequently slowly decreasing
the cuff pressure P.sub.c and terminates the BP measurement by
completely deflating the cuff 510 after the BP value of the subject
has been determined during the slow decreasing of the cuff pressure
P.sub.c by the BP measuring device 508; a pulse amplitude/cuff
pressure (PA/CP) memory area 680 of the RAM 630 stores each of the
successive pulse amplitudes detected by the band-pass filter 522,
523 and a cuff pressure value P.sub.c at the time of detection of
each pulse amplitude, in the order of detection of the pulse
amplitudes. The control device 526 or CPU 528 determines an
envelope representing a relationship between (a) the pulse
amplitudes detected during the quick cuff inflation period by the
band-pass filter 522, 523 and (b) the cuff pressure values P.sub.c
at the times of detection of those pulse amplitudes. In addition,
the CPU 528 operates for estimating a BP value of the subject,
based on the determined envelope, according to a prescribed rule or
relationship.
The control device 526 determines, in advance, a first envelope
based on (a) a considerable great number of pulse amplitudes
obtained by the BP measuring device 508 in measuring a BP value of
the subject and (b) the cuff pressure values P.sub.c when those
pulse amplitudes are obtained. Since the first envelope is
determined based on the many pulse amplitudes, the first envelope
has a considerably high accuracy. Additionally, this envelope has a
curved pattern proper to the subject. In a manner similar to that
employed for determining the above envelope, the control device 526
determines a second envelope or curve connecting a considerable
small number of pulse amplitudes obtained during a quick cuff
inflation, over the respective cuff pressure values P.sub.c when
those pulse amplitudes are obtained. Based on the second envelope,
the CPU 528 estimates a BP value of the subject. For example, like
in the oscillometric BP measurement technique, a cuff pressure
value P.sub.c corresponding to a maximum value of the second
envelope is estimated as a mean BP value of the subject; and two
cuff pressure values P.sub.c corresponding to two maximum slopes of
the second envelope are estimated as a systolic and a diastolic BP
value of the subject (the higher cuff pressure P.sub.c is estimated
as the systolic BP value and the lower cuff pressure P.sub.c is
estimated as the diastolic BP value).
In this modified manner, the control device 526 or CPU 528 operates
for determining, based on an estimated BP value of the subject, a
modified target pressure P.sub.CMR to which the cuff pressure
P.sub.c is quickly increased in a BP measurement. The CPU 528
controls the air pump 514 and the pressure regulator valve 516 to
slowly decrease the cuff pressure P.sub.c after the pressure
P.sub.c has been raised up to the modified target pressure
P.sub.CMR. The CPU 528 also operates for identifying a subject's
blood pressure abnormality by comparing the estimated BP value with
a reference pressure value or range. If the subject's abnormal
blood pressure is identified, the CPU 528 controls the output
device 538 to indicate that the blood pressure of the subject is
abnormal.
Hereinafter, there will be described the operation of the BP
apparatus 600 as modified as described above, by reference to the
flow charts of FIGS. 46 and 47 employed in place of the flow charts
of FIGS. 36 and 37.
Steps SB201 through SB205 are the same as Steps SA201 through SA205
of FIG. 36, and are carried out to quickly increase the cuff
pressure P.sub.c, subsequently slowly decrease the cuff pressure
P.sub.c, and judge whether one pulse has been supplied from the
first band-pass filter 522.
At the following Step SB206, the CPU 528 stores, in the PA/CP
memory area 680 of the RAM 630, the amplitude of one pulse supplied
from the first band-pass filter 522 and the cuff pressure value Pc
at the time of supplying of the one-pulse signal SM1. Step SB207 is
the same as Step SA207 of FIG. 36, and is carried out to measure an
actual BP value of the subject. Steps SB208 through SB210 are the
same as Steps SA208 through SA210 of FIG. 36, and are executed to
judge whether the BP measurement has been completed, output the
measured BP value or values, and reduce the cuff pressure P.sub.c
down to atmospheric pressure, thereby releasing the subject's upper
arm from the pressing of the cuff 510.
At the end of a BP measurement carried out at Steps SB201 through
SB210, a considerably great number of pulse amplitudes and
corresponding cuff pressure values P.sub.c which are obtained in
the BP measurement, are stored in the PA/CP memory area 680.
Therefore, at the following Step SB211, the control device 526 or
CPU 528 determines a first envelope, H.sub.1, connecting data
points representing the pulse amplitudes, PA, and the corresponding
cuff pressure values P.sub.c, as shown in FIG. 48. Since the first
envelope H.sub.1 is obtained based on the considerably great number
of data points obtained in the BP measurement, the first envelope
H.sub.1 enjoys a considerably high accuracy, and represents a
curved pattern proper to the subject.
Step SB212 is the same as Step SA214 of FIG. 36. If a positive
judgment is made at Step SB212, the CPU 528 carries out Steps SB213
through SB217 that are the same as Steps SA215 through SA219 of
FIG. 37, thereby quickly increasing the cuff pressure P.sub.c. At
the following Step SB220, the CPU 528 judges whether one pulse has
been supplied from the first band-pass filter 522 during the quick
increasing of the cuff pressure P.sub.c, i.e., during the quick
cuff inflation period. However, the CPU 528 adopts, as a correct or
true pulse, only a pulse which falls within a reference range, T
(pulse period) .+-.20%. The pulse period T is defined as the time
distance between the respective upper (or lower) peaks of the last
pair of successive two pulses each pulse of which has been adopted
as a true pulse. If the current pulse does not fall within the
reference range, i.e., time window, the CPU 528 discards the pulse
as noise. If a positive judgment is made at Step SB211, the control
of the CPU 528 goes to Step SB219 to store, in the PA/CP memory
area 680, the amplitude of the pulse and the cuff pressure value
P.sub.c at the time of supplying of the pulse amplitude. Step SB219
is followed by Step SB220 to determine, according to an envelope
determination algorithm, a second envelope, H.sub.2, representing a
relationship between (a) the pulse amplitudes obtained during the
quick cuff inflation period and (b) the cuff pressure values
P.sub.c when those pulse amplitudes are obtained. Since the number
of the data points used to determine the second envelope H.sub.2 is
considerably small, the CPU 528 modifies the original polygonal
line H.sub.2 obtained by connecting the data points with one
another, in such a manner that the modified curved line, i.e.,
second envelope H.sub.2 is similar to the pattern of the first
envelope H.sub.1. FIGS. 49(A), 49(B), 49(C), and 49(D) shows
examples of the second envelope H.sub.2 which can be obtained at
Step SB220.
At the following Step SB221, the CPU 528 estimates a BP value of
the subject based on the second envelope H.sub.2 which is
determined at Step SB220 based on the pulses obtained during the
quick cuff inflation period. Specifically described, like the
oscillometric BP determination technique, a cuff pressure value
corresponding to the maximum value of the second envelope H.sub.2
is determined as an estimated mean BP value of the subject, and two
cuff pressure values corresponding to two maximum slopes of the
second envelope H.sub.2 are determined as an estimated systolic and
an estimated diastolic BP value of the subject (the higher cuff
pressure is determined as the estimated systolic BP value and the
lower cuff pressure is determined as the estimated diastolic BP
value).
Step SB221 is followed by Step SB222 to judge whether the BP
estimation at Step SB221 has been completed. If a negative judgment
is made at Step SB222, the control of the CPU 528 goes back to Step
SB217 and the following steps to read in subsequent pulses. On the
other hand, if a positive judgment is made, the control goes to
Steps SB223 through SB226 that are the same as Steps SA224 through
SA227. If at Step SB523 the CPU 528 judges that the estimated BP
value of the subject determined at Step SB221 is abnormal, the CPU
528 controls, at Step SB224, the output device 538 to indicate that
the estimated BP value of the subject is abnormal. On the other
hand, if at Step SB523 the CPU 528 does not judge that the
estimated BP value of the subject determined at Step SB221 is
abnormal, the CPU 528 determines, at Step SB225, a modified target
pressure P.sub.CMR. If the actual cuff pressure P.sub.c reaches a
pressure higher by an excess or buffer value .alpha. than the
modified target pressure P.sub.CMR, the control of the CPU 528 goes
back to Step SB204 and the following steps.
In the modified BP monitor operation in accordance with the flow
charts of FIGS. 46 and 47, the first band-pass filter 522 serves as
a pulse detector which detects pulse amplitudes while the cuff
pressure P.sub.c is quickly increased. Step SB220 and a portion of
the control device 526 for carrying out this step cooperate with
each other to serve as means for determining a second envelope
H.sub.2 representing a relationship between (a) the respective
amplitudes of the pulses detected by the pulse detector during the
quick cuff inflation period and (b) the respective cuff pressure
values at the times of detection of those pulse amplitudes. Step
SB221 and a portion of the control device 526 for carrying out this
step cooperate with each other to serve as means for estimating a
BP value of the subject, based on the second envelope H.sub.2
determined at Step SB220, according to a prescribed BP estimation
rule such as a known oscillometric BP determination rule. Thus, the
apparatus 600 modified as described above provides a considerably
accurate estimated BP value of the subject based on the second
envelope H.sub.2 obtained in each quick cuff inflation period
before each slow cuff deflation period, i.e., shortly after the
beginning of each cyclic BP measurement carried out in the
BP-monitor mode. Thus, medical workers can quickly know the
considerably accurate BP value or values of the subject.
In addition, since at Step SB218 the CPU 528 adopts only pulses
each of which falls inside an appropriate time window, i.e.,
discards "noise" pulses which do not fall inside the time window,
the estimated BP values of the subject enjoy a high
reliability.
Step SB225 and a portion of the control device 526 for carrying out
this step cooperate with each other to serve as means for
determining a modified target pressure P.sub.CMR based on an
estimated BP value of the subject provided at Step SB221; and the
pressure regulator valve 516 and a portion of the control device
526 for controlling the valve 516 cooperate with each other to
serve as means for regulating the cuff pressure P.sub.c by quickly
increasing the pressure P.sub.c up to a pressure higher by the
access .alpha. than the determined target pressure P.sub.CMR and
then slowly decreasing the pressure P.sub.c. Since the pressure
higher by the access .alpha. than the modified target pressure
P.sub.CMR is a necessary and adequate pressure higher than an
estimated systolic BP value of the subject, the BP apparatus 600
effectively prevents the cuff pressure P.sub.c from being increased
up to an unnecessarily high value, thereby preventing the subject
from feeling discomfort due to the unnecessarily high pressure.
Step SB223 and a portion of the control device 526 for carrying out
this step cooperate with each other to serve as judging means for
judging whether the blood pressure of the subject is abnormal, by
comparing the estimated BP value of the subject obtained at Step
SB221, with a reference pressure value or range. The output device
538 and a portion of the control device 526 for controlling the
output device 538 cooperate with each other to serve as means for
outputting an indication that the blood pressure of the subject is
abnormal, when the judging means makes a positive judgment.
Therefore, the present apparatus 600 as modified also ensures that
medical workers can recognize a subject's blood pressure
abnormality at an early point of time in a quick cuff inflation
period. Accordingly, the medical workers such as doctors can take
appropriate medical actions on the subject.
While in the BP monitor operation in accordance with the flow
charts of FIGS. 36 and 37 the relationships determined at Step
SA212 once in the first BP monitor cycle following each BP
measurement are used to estimate a BP value of the subject also in
each of the subsequent BP monitor cycles, without being updated, it
is possible to modify the BP apparatus 600 to carry out BP
measurements at regular intervals of time and periodically
determine new relationships based on the BP value or values
determined in each BP measurement.
Although the cuff pressure P.sub.c is monotonously increased during
each quick cuff inflation period and pulse amplitudes are obtained
in the process in which the cuff pressure P.sub.c is increased in
that manner, it is possible to stepwise increase the cuff pressure
P.sub.c while holding the pressure P.sub.c at pressure steps each
for a prescribed short duration, so that the control device 526
obtains one or more pulses when the pressure P.sub.c is held at
each step. In the latter case, the control device 526 can utilize
pulses having more accurate waveforms.
While at Step SB221 of the flow chart of FIG. 47 the oscillometric
BP determination technique is utilized to estimate a BP value of
the subject based on the second envelope H.sub.2, it is possible to
employ other BP estimation methods or techniques. For example, it
is possible to employ an easier technique to determine, as an
estimated systolic, mean, or diastolic blood pressure of the
subject, a cuff pressure value P.sub.c corresponding to a point of
intersection of the second envelope H.sub.2 and a broken line
corresponding to a prescribed pulse amplitude, as shown in FIG.
49(A).
Referring next to FIG. 50, there is shown an automatic blood
pressure (BP) measuring apparatus 700 as a sixth embodiment of the
present invention.
In FIG. 50, reference numeral 710 designates an inflatable cuff
adapted to be wound around an upper arm of a living subject (e.g.,
patient) so as to press the upper arm. The cuff 710 includes an
inflatable bag (not shown). The inflatable bag of the cuff 510 is
connected via piping 720 to a pressure sensor 712, a quick
deflation valve 714, a slow deflation valve 716, and an air pump
718.
The pressure sensor 712 detects an air pressure in the cuff 710
("cuff pressure") and supplies a detection signal, SP, to a
cuff-pressure detector circuit 722 and a pulse-wave detector
circuit 724. The cuff-pressure detector circuit 722 includes a
low-pass filter (not shown) which permits only a static-pressure
component of the detection signal SP to pass therethrough, thereby
supplying a cuff-pressure signal, SK, representing the detected
static cuff pressure, P.sub.c, to a control circuit 728 via an
analog-to-digital (A/D) converter 726. The pulse-wave detector
circuit 724 includes a band-pass filter (not shown) which permits
only an oscillation component of the detection signal SP to pass
therethrough, thereby supplying a pulse-wave signal, SM,
representing a pulse wave of the subject, to the control circuit
728 via the A/D converter 726. The pulse wave is generated in the
cuff 710 because of the pulsation of arteries of the upper arm
under the cuff 710 in synchronism with the heartbeats of the
subject, while the cuff pressure P.sub.c changes within an
appropriate pressure range. Thus, the pulse wave generated in the
cuff 710 is obtained as the oscillation component of the detection
signal SP supplied from the pressure sensor 712.
The control circuit 728 is essentially constituted by a
microcomputer including a CPU 730, a ROM 732, a RAM 734, and an
output interface 736. The CPU 730 receives the digital signals SK
and SM from the A/D converter 726, and processes those signals by
utilizing the temporary-storage function of the RAM 734 and the
control programs or algorithms pre-stored in the ROM 732. The CPU
730 supplies drive signals to the quick deflation valve 714, slow
deflation valve 716, and air pump 718, to measure a blood pressure
(BP) value of the subject. The CPU 730 carries out the pre-stored
algorithms to supply, to an output device 738, a BP signal
representing the measured BP value, a measurement-condition signal
indicating whether the condition of measurement of the BP value is
sufficiently proper, and a pulse-amplitude signal representing
respective amplitudes of a series of successive pulses of the pulse
wave (i.e., pulse-wave signal SM). The output device 738 includes
an image display panel (not shown; e.g., liquid-crystal display
panel) which has a matrix of picture elements. The output device
738 may further include a printer, as needed, which records using
an ink an image on a recording sheet. The output device 738
outputs, on the image display panel or the recording sheet, the BP
value of the subject, the propriety or non-propriety of the
condition of the BP measurement, and the series of pulse
amplitudes. Reference numeral 740 designates a START/STOP button
manually operable for alternately starting and stopping the
operation of the present BP measuring apparatus 700.
Hereinafter, there will be described the automatic BP measuring
operation of the BP apparatus 700 constructed as described above,
by reference to the flow charts of FIGS. 51 and 52.
Initially, at Step S301, the CPU 730 judges whether the START/STOP
button 740 has been operated for starting the operation of the
present apparatus 700, based on a START or STOP signal supplied
from the button 740. If a negative judgment is made at Step S301,
the control of the CPU 730 waits for receiving the START signal
from the button 740. Meanwhile, if a positive judgment is made, the
control of the CPU 730 proceeds with Step S302 to close the quick
and slow deflation valves 714, 716 and drive the air pump 718 so as
to start supplying a pressurized air to the inflatable cuff 710 and
thereby increasing the air pressure in the cuff 510, i.e., cuff
pressure P.sub.c.
Step S302 is followed by Step S303 to judge whether the cuff
pressure P.sub.c has been increased up to a prescribed target
pressure, P.sub.m (e.g., 180 mmHg), which is sufficiently higher
than a systolic blood pressure of the subject. If a negative
judgment is made at Step S303, the CPU 730 repeats Step S303 to
continue to increase the cuff pressure P.sub.c. Meanwhile, if a
positive judgment is made at Step S301, the control of the CPU 730
proceeds with Step S304 to stop the air pump 718 and open the slow
deflation valve 716 so as to start deflating the cuff 710, i.e.,
decreasing the cuff pressure P.sub.c. This cuff deflation or
pressure decreasing is carried out slowly at a rate of, e.g., 2 to
3 mmHg/sec suitable for BP measurements. During this slow cuff
deflation, Steps S305 and S306 are repeatedly carried out for
determining a BP value of the subject.
At Step S305, the BP determination subroutine represented by the
flow chart of FIG. 52 is repeated at a short cycle or period, e.g.,
every four milliseconds. In this subroutine, respective amplitudes,
R, of a series of successive pulses of the pulse wave signal SM are
determined and pre-treated, and a BP value or values of the subject
is or are determined based on the pulse amplitudes R according to a
known BP determination algorithm.
First, at Step ST1, the CPU 730 reads, at a sampling period,
respective magnitudes of the pulse wave signal SM supplied thereto
from the A/D converter 726, and judges whether the CPU 730 has
received a length of the pulse wave signal SM corresponding to one
pulse having an amplitude, i.e., one cycle of heartbeat of the
subject. If a negative judgment is made at Step ST1, the CPU 730
repeats Step ST1. Meanwhile, if a positive judgment is made at Step
ST1, that is, if the CPU 730 reads in an upper peak and a lower
peak of one pulse, the control of the CPU 730 proceeds with Step
ST2 to calculate an amplitude, R.sub.i, of the pulse by subtracting
the lower-peak magnitude thereof from the upper-peak magnitude
thereof. Step ST2 is followed by Step ST3 to judge whether the
calculated pulse amplitude R.sub.i is abnormal, by identifying such
a change of the current amplitude R.sub.i from the preceding
amplitude R.sub.i-1 which cannot physiologically be expected to
occur. For example, in the case where the current amplitude R.sub.i
is obtained before the cuff pressure P.sub.c is decreased below a
mean BP value of the subject, the CPU 730 makes a positive or
"abnormality" judgment if the current amplitude R.sub.i is smaller
than half the preceding amplitude R.sub.i-1 or greater than four
times the same R.sub.i-1 ; and, in the case where the current
amplitude R.sub.i is obtained after the cuff pressure P.sub.c is
decreased below the mean BP value of the subject, the CPU 730 makes
an "abnormality" judgment if the current amplitude R.sub.i is
smaller than half the preceding amplitude R.sub.i-1 or greater than
one and a half times the same R.sub.i-1.
If a positive judgment is made at Step ST3, the control of the CPU
730 goes back to Step ST1 and the following steps. On the other
hand, if a negative judgment is made at Step ST3, the control goes
to Step ST4 to store, in an appropriate memory area of the RAM 734,
the current pulse amplitude R.sub.i and a cuff pressure value
P.sub.c at the time of supplying of the pulse amplitude R.sub.i.
Step ST4 is followed by Step ST5 to judge whether the current
amplitude R.sub.i is the first normal amplitude following the last
abnormal amplitude. If a negative judgment is made at Step ST5, the
control of the CPU 730 bypasses Step ST6 and goes to Step ST7. On
the other hand, if a positive judgment is made at Step ST5, the
control goes to Step ST6 to carry out the "amp-filter" treatment
that is disclosed in, e.g., the aforementioned non-examined
Japanese patent application laid open under Publication No.
63-51837. That is, one or more abnormal amplitudes R.sub.i-k, . . .
, R.sub.i-2, R.sub.i-1 preceding the current normal amplitude
R.sub.i is or are subjected to linear interpolation based on the
current amplitude R.sub.i and the normal amplitude R.sub.i-k-1
preceding the one or more abnormal amplitudes R.sub.i-k, . . . ,
R.sub.i-2, R.sub.i-1.
At the following Steps ST7 and ST8, the series of pulse amplitudes
R.sub.n that have been subjected to the amp-filter treatment at
Step ST6, as needed, are subjected to the "median-filter" treatment
so as to smoothen the amplitudes R.sub.n. The median-filter
treatment is disclosed in, e.g., the above Japanese patent
application. Specifically, at Step ST7, the CPU 730 selects an odd
number (e.g., five) of successive pulse amplitudes R.sub.i-4,
R.sub.i-3, R.sub.i-2, R.sub.i-1, R.sub.i including the current
amplitude R.sub.i. Step ST7 is followed by Step ST8 to replace the
middle amplitude R.sub.i-2 by the third greatest amplitude R.sub.j
of all the five amplitudes. In the present embodiment, Steps ST5 to
ST8 and a portion of the control circuit 728 for carrying out those
steps cooperate with each other to serve as means for smoothening
the detected pulse amplitudes R.sub.n. At Step ST7, the CPU 730 may
be programmed to select three or seven or other odd number of
successive pulse amplitudes other than five successive
amplitudes.
After at Step ST8 the series of pulse amplitudes R.sub.n are
smoothened, the control of the CPU 730 proceeds with Step ST9,
i.e., BP determination algorithm for determining a systolic and a
diastolic BP value of the subject based on the thus smoothened
pulse amplitudes, S.sub.n. Specifically described, the respective
cuff pressure values P.sub.c corresponding to the two pulse
amplitudes S.sub.i at which the series of pulse amplitudes S.sub.n
significantly greatly change, are selected, and the selected two
pressure values P.sub.c are determined as the systolic and
diastolic BP values of the subject. The two determined BP values
may be corrected, as needed, based on a prescribed relationship
between systolic and diastolic BP values and/or a prescribed
relationship between systolic or diastolic BP value and mean BP
value. The two determined BP values are stored in an appropriate
memory area of the RAM 734. Thus, in the present embodiment, the BP
values of the subject are determined based on a pulse wave in the
form of a heartbeat-synchronous signal wave, i.e., a pressure
oscillation produced in the cuff 710 in synchronism with the
heartbeats of the subject, the cuff 710 being wound around a body
portion of the subject to press the body portion.
Back to the flow chart of FIG. 51, the control of the CPU 730
subsequently goes to Step S306 to judge whether the BP
determination subroutine at Step S305 has been completed. For a
while shortly after the beginning of the slow decreasing of the
cuff pressure P.sub.c, a sufficient number of pulse amplitudes
S.sub.n have not been obtained. Therefore, the CPU 730 repeats
Steps S305 and S306. Meanwhile, if a positive judgment is made at
Step S306, that is, if the BP values of the subject have been
determined at Step ST9 of FIG. 52, the control of the CPU 730 goes
to Step S307.
At Step S307, the CPU 730 opens the quick deflation valve 715 to
completely deflate the cuff 710, i.e., reduce the cuff pressure
P.sub.c down to atmospheric pressure. At the following Steps S308,
S309, and S310, the CPU 730 calculates a correction degree, C,
i.e., degree of correction of the series of smoothened pulse
amplitudes S.sub.n from the series of detected pulse amplitudes
R.sub.n. More specifically, at Step S308, the CPU 730 calculates a
sum, SD of respective absolute values, .vertline.S.sub.i -R.sub.i
.vertline., each of which is obtained as a difference of pulse
amplitudes R.sub.i and S.sub.i which correspond to a cuff pressure
value P.sub.c within a prescribed pressure range, according to the
following expression (3):
The above-mentioned pressure range may be pre-determined to cover
the pulse amplitudes R.sub.i, S.sub.i ranging from the pulse
amplitude R.sub.u-1, S.sub.u-1 outside and adjacent the pulse
amplitude R.sub.u, S.sub.u corresponding to the systolic BP value
of the subject determined at Step ST9, to the pulse amplitude
R.sub.t+1, S.sub.t+1 outside and adjacent the pulse amplitude
R.sub.t, S.sub.t corresponding to the determined diastolic BP value
of the subject.
At the following Step S309, the CPU 730 calculates a sum, SS, of
respective smoothened pulse amplitudes S.sub.i which correspond to
the cuff pressure values P.sub.c within the above-mentioned
pressure range, according to the following expression (4):
Step S309 is followed by Step S310 to calculate, as the correction
degree C, a percentage of the sum SD to the sum SS, according to
the following expression (5):
Thus, in the present embodiment, Steps S308 to S310 and a portion
of the control circuit 728 for carrying out those steps cooperate
with each other to serve as means for calculating the correction
degree C.
In FIG. 53, the first sum SD corresponds to a first area as a sum
of shadowed areas, A; the second sum SS corresponds to a second
area bounded by a polygonal line representing the series of
smoothened pulse amplitudes S.sub.i and a base line parallel to the
axis of abscissa, i.e., axis indicative of cuff pressure P.sub.c.
Therefore, the correction degree C corresponds to a ratio of the
first area to the second area.
Step S310 is followed by Step S311 to control the output device 738
and/or another output device (not shown) to output the systolic and
diastolic BP values, and pulse rate, of the subject. The pulse rate
is determined based on the difference between the times of
detection of respective upper (or lower) peaks of two successive
pulses. In addition, at Step S311, the CPU 730 controls the output
device 738 to record, on a recording sheet 742 shown in FIG. 53, a
first graphic representation 744 including the first series of
detected pulse amplitudes R and the second series of smoothened
pulse amplitudes S, superimposed on each other, in a
two-dimensional coordinate system defined by a first axis
indicative of cuff pressure P.sub.c and a second axis indicative of
pulse amplitudes R, S. The output device 738 also records, on the
sheet 742, a second graphic representation 746 in a side-by-side
relation with the first graph 744. The second graph 746 is
indicative of a propriety of measurement condition, i.e., a
correction degree C. The length of the "black" horizontal bar 746
corresponds to the determined correction degree C. The longer the
bar 746 is, the higher the correction degree C is. The higher
correction degree C indicates the higher degree of mixing of
"noise" pulses with true pulses. In the first graph 744, the first
series of detected pulse amplitudes R are indicated at vertical
lines, and the second series of smoothened pulse amplitudes S are
indicated at a polygonal line. The shadowed areas A bounded by (a)
the envelope of the vertical lines and (b) the polygonal line
represents the first sum SD. The two cuff pressure values P.sub.c
corresponding to the systolic and diastolic BP values of the
subject determined at Step ST9, are indicated at symbols
.tangle-solidup. and .DELTA., respectively, recorded along the
first axis. The second graph 746 includes three marks "L", "N", and
"H" indicating a low, a normal, and a high correction degree C,
i.e., three degrees of mixing of "noise" pulses with true pulses,
respectively. Thus, the second graph 746 indicates the degree of
propriety of the current measurement condition under which the
current BP values of the subject have been measured. Medical
workers can recognize the current measurement condition by
comparing the length of the "black" horizontal bar C with the marks
"L", "N" or "H". For example, the normal correction degree C
corresponding to the mark "N" may be selected at 5%, and the high
correction degree C corresponding to the mark "H" may be selected
at 9%. In the present embodiment, the control circuit 728 serves as
a control device which controls the output device 738.
As is apparent from the foregoing description, the BP measuring
apparatus 700 operates in such a way that at Step S311 the output
device 738 outputs the first series of detected or sampled pulse
amplitudes R and the second series of smoothened or processed pulse
amplitudes S, the two sorts of pulse amplitudes R, S being
superimposed on each other in the common two-dimensional graph 744.
Therefore, medical workers such as doctors can visually recognize
the differences, D.sub.i, of the detected pulse amplitudes R.sub.i
and the corresponding smoothened pulse amplitudes S.sub.i. The
differences D.sub.i correspond to the sun of areas A shown in FIG.
53. The differences D.sub.i may be increased due to external causes
such as the physical motion of the subject or noise due to
peripheral devices. Medical workers can easily judge whether the
measured BP values of the subject contain excessively large errors
due to the external causes, by recognizing the respective positions
of the differences D.sub.i, i.e., areas A with respect to the first
axis, i.e., cuff-pressure axis of the common two-dimensional graph
744. That is, the medical workers can easily identify whether the
condition of the BP measurement is proper. For example, in the case
where the sum SD of the differences D.sub.i is excessively large
because the series of smoothened pulse amplitudes S have been
excessively largely corrected particularly in a range of cuff
pressure P.sub.c between the determined systolic and diastolic BP
values of the subject indicated at the respective symbols
.tangle-solidup., .DELTA. in the graph 744, medical workers can
easily judge that the series of detected pulse amplitudes R have
been excessively largely influenced by external causes and that the
accuracy of measured BP values of the subject is insufficiently low
and the condition of the BP measurement is not appropriate.
Since in the present embodiment the first series of detected pulse
amplitudes R are indicated by vertical lines, the second series of
smoothened pulse amplitudes S are indicated by a polygonal line,
and the differences D of the two sorts of pulse amplitudes R, S are
indicated by the shadowed areas A bounded by (a) the envelope of
the vertical lines and (b) the polygonal line, observers can easily
recognize the magnitude or amount of the sum of differences D,
i.e., first sum SD.
In the present embodiment, the control circuit 728 or CPU 730
calculates the correction degree C as the percentage of the sum of
areas A to the area bounded by (a) the polygonal line of the
smoothened pulse amplitudes S and (b) the base line. The correction
degree C indicates the degree of correction of the smoothened pulse
amplitudes S from the detected pulse amplitudes R. The correction
degree C is indicated by the horizontal bar in the second graph 746
provided in a side-by-side relation with the first graph 744 on the
recording sheet 742 or on the image display panel (not shown) of
the output device 738. Thus, observers can visually know what
percent of correction has been made on the detected pulse
amplitudes R. The observers can judge, based on the correction
degree C, whether the measured BP values of the subject contain
excessively large errors due to external factors, i.e., whether the
condition of the BP measurement is proper. In addition, the second
graph 746 includes the three marks or indicias "L" (i.e., `noise is
low`), "N" (`noise is normal`) and "H" (`noise is high`)
respectively indicating the three degrees of propriety of the
measurement condition. Thus, operators who are not familiar with
the BP apparatus 700 can easily judge, based on the horizontal bar
and the marks of the second graph 746, whether the measurement
condition is proper or appropriate. For example, in the case where
the right-hand end of the horizontal bar indicative of the
correction degree C reaches a position between the marks "L" and
"N", that is, a position where the correction degree C is smaller
than 5%, the operators can judge that the condition of the BP
measurement is proper. In the present embodiment, the correction
degree C indicates the degree of propriety of the measurement
condition, and the horizontal bar representing the correction
degree C is output in a side-by-side relation with the marks "L",
"N", "H" each representing a degree of propriety of measurement
condition.
FIGS. 54, 55, 56, and 57 shows other forms of expression each
corresponding to the two-dimensional graph 744 shown in FIG. 53. In
FIG. 54, the series of smoothened pulse amplitudes S are indicated
in the same manner as that employed in FIG. 53, but the series of
detected pulse amplitudes R are indicated by not vertical lines but
a polygonal line, like the smoothened pulse amplitudes S. In
addition, areas A bounded by those two polygonal lines are not
shadowed. Also in this case, observers can clearly recognize the
differences D.sub.i of the two sorts of pulse amplitudes R, S in
the common two-dimensional graph, and can easily judge whether the
measured BP values of the subject contain excessively large errors
due to external factors, i.e., whether the measurement condition is
proper, based on (a) the sum of differences D.sub.i and (b) the
respective positions of the differences D.sub.i with respect to the
first axis of the common two-dimensional graph.
In the two-dimensional graph shown in FIG. 54, a portion or
portions of the polygonal line of the smoothened pulse amplitudes S
which is or are separate from a corresponding portion or portions
of the polygonal line of the detected pulse amplitudes R,
indicate(s) that data correction has been carried out on the
portion or portions. Therefore, observes can easily recognize the
differences D.sub.i of the two sorts of pulse amplitudes R, S.
In the two-dimensional graph shown in FIG. 55, both the two sorts
of pulse amplitudes R, S are indicated at bars, and areas A
corresponding to the differences D.sub.i of the two sorts of pulse
amplitudes R, S are indicated in a color or pattern different from
a color or pattern used to indicate the other portions of the bars.
For example, a light and a dark color may be used to distinguish
the areas A and the other portions from each other. In this case,
too, observers can clearly recognize the differences D.sub.i of the
two sorts of pulse amplitudes R, S in the common two-dimensional
graph, and can easily judge whether the measured BP values of the
subject contain excessively large errors due to external factors,
i.e., whether the measurement condition is proper, based on (a) the
sum of differences D.sub.i and (b) the respective positions of the
differences D.sub.i with respect to the first axis of the common
two-dimensional graph.
In the two-dimensional graph shown in FIG. 56, one of the two sorts
of pulse amplitudes R, S (the smoothened pulse amplitudes S in the
figure) are indicated at a polygonal line and the other (the
detected pulse amplitudes R in the figure) are indicated at
vertical bars. In this case, observers can visually recognize (a) a
vertical bar or bars higher than a corresponding portion or
portions of the polygonal line, (b) a portion or portions of the
polygonal line higher than a corresponding vertical bar or bars,
and (c) the differences D.sub.i of the heights of the higher bars
and the heights of the corresponding portions of the polygonal line
and the differences D.sub.i of the heights of the higher portions
of the polygonal line and the heights of the corresponding bars.
Thus, the observers can clearly recognize the differences D.sub.i
of the two sorts of pulse amplitudes R, S in the common
two-dimensional graph, and can easily judge whether the measured BP
values of the subject contain excessively large errors due to
external factors, i.e., whether the measurement condition is
proper, based on (a) the sum of differences D.sub.i and (b) the
respective positions of the differences D.sub.i with respect to the
first axis of the common two-dimensional graph.
In the two-dimensional graph shown in FIG. 57, one of the two sorts
of pulse amplitudes R, S are indicated at vertical lines and the
other are indicated at a polygonal line, like in the graph shown in
FIG. 53. However, the differences D.sub.i of the two sorts of pulse
amplitudes R, S are not indicated at shadowed areas A, unlike the
graph of FIG. 53. In this case, however, observers can visually
recognize (a) a vertical line or lines higher than a corresponding
portion or portions of the polygonal line, (b) a portion or
portions of the polygonal line higher than a corresponding vertical
line or lines, and (c) the differences D.sub.i of the heights of
the higher vertical lines and the heights of the corresponding
portions of the polygonal line and the differences D.sub.i of the
heights of the higher portions of the polygonal line and the
heights of the corresponding vertical lines. Thus, the observers
can clearly recognize the differences D.sub.i of the two sorts of
pulse amplitudes R, S in the common two-dimensional graph, and can
easily judge whether the measured BP values of the subject contain
excessively large errors due to external factors, i.e., whether the
measurement condition is proper, based on (a) the sum of
differences D.sub.i and (b) the respective positions of the
differences D.sub.i with respect to the first axis of the common
two-dimensional graph.
In each of the two-dimensional graphs shown in FIGS. 54-57, the
measured systolic and diastolic BP values of the subject are
indicated at symbols .tangle-solidup., .DELTA. provided along the
first axis, i.e., cuff-pressure axis of each two-dimensional graph.
Therefore, observers can easily specify, in the two-dimensional
graph, a cuff-pressure range to be utilized in judging whether the
measurement condition is proper (e.g., cuff-pressure range between
the measured systolic and diastolic BP values).
A horizontal bar representing a determined correction degree C may
be indicated together with each of the graphs shown in FIGS. 54-57,
like the second graph 746 indicated with the first graph 744 shown
in FIG. 53. Alternatively, each of the graphs of FIGS. 54-57 may
not be accompanied by a horizontal bar representing a correction
degree C. Otherwise, the BP measuring apparatus 700 may be provided
with another output device which indicates the correction degree C,
i.e., degree of propriety of the measurement condition.
The output device 738 may be modified to output a correction degree
C in digits in a measurement-condition indication area 846 provided
on a recording sheet 842 shown in FIG. 58. A pulse-amplitude
indication area like the first graph 744 shown in FIG. 53 is not
provided on the recording sheet 842. Below the correction degree C
indicated in a digit or digits, notes are provided which read as
follows: "3>C: NOISE IS LOW", "6>C.gtoreq.3: NOISE IS
NORMAL", and "C.gtoreq.6: NOISE IS HIGH (ANOTHER MEASUREMENT IS
NECESSARY)". Those notes may be used as standards in judging
whether the correction degree C is excessively high. In this case,
too, observers can easily judge whether the measured BP values of
the subject contain excessively large errors due to external
factors, i.e., whether the measurement conditions is proper, based
on the output data 846 recorded on the sheet 842.
The indication of the degree of propriety of the measurement
condition may otherwise be made than shown in FIG. 58 where the
correction degree C in digits is recorded on the sheet 842. For
example, the BP apparatus 700 may be modified to select one of
evaluation messages, such as "NOISE IS LOW" or "NOISE IS HIGH",
which corresponds to the determined correction degree C, and output
the selected message in the measurement-condition indication area
846 of the recording sheet 842. In the latter case, as shown in
FIG. 59, Steps S312, S313a, S313b, and S313c are provided after
Step S310 of the flow chart of FIG. 51. More specifically, at Step
S312, the CPU 730 compares the determined correction degree C with
two reference values respectively corresponding to the evaluations
of "NOISE IS NORMAL" and "NOISE IS HIGH", and judges whether the
determined correction degree C is smaller than 3 as the first
reference value, whether the degree C is not smaller than 3 and
smaller than 6 as the second reference value, or whether the degree
C is not smaller than 6. In the case of C <3, the control of the
CPU 730 goes to Step S313a to select an evaluation message "NOISE
IS LOW" and store the message in a memory area, M, of the RAM 734;
in the case of 6>C.gtoreq.3, the control goes to Step S313b to
select an evaluation message "NOISE IS NORMAL" and store the
message in the memory M; and, in the case of C.gtoreq.6, the
control goes to Step S313c to select an evaluation message "NOISE
IS HIGH" and store the message in the memory M. Following Step
S313a, S313b, or S313c, the control of the CPU 730 goes to Step
S314 provided in place of Step S311 of FIG. 51. At Step S314, the
CPU 730 controls the output device 738 to output, in place of the
correction degree C, the evaluation message selected at Step S313a,
S313b, or S313c, in the measurement-condition indication area 846
of the recording sheet 842. Otherwise, the BP apparatus 700 may be
provided with a plurality of lamps related with different
correction degrees C, so that the BP apparatus 700 may light one of
the lamps which corresponds to a determined correction degree
C.
It is to be understood that the sixth embodiment may be modified in
other manners.
For example, while the BP apparatus 700 measures the BP values of
the subject by utilizing, as a heartbeat-synchronous signal wave, a
pulse wave produced in the cuff 710, it is possible to provide a
microphone in the cuff 710 and detect using the microphone the
Korotkoff sounds that are arterial sounds produced from the
arteries of a body portion being pressed by the cuff 710. In the
latter case, the Korotkoff sounds are utilized as a
heartbeat-synchronous signal wave in BP measurements.
In the sixth embodiment, Step ST3 and a portion of the control
circuit 728 for carrying out this step cooperate with each other to
serve as means for judging whether each detected or determined
pulse amplitude R.sub.i falls within a reference range and, if the
pulse amplitude R.sub.i does not fall within the reference range,
judging that the pulse amplitude R.sub.i is abnormal. Steps ST5 and
ST6 and a portion of the control circuit 728 for carrying out these
steps cooperate with each other to serve as means for replacing an
abnormal pulse amplitude or amplitudes R.sub.i with a value or
values obtained by interpolating two normal pulse amplitudes
R.sub.i sandwiching the abnormal amplitude or amplitudes R.sub.i.
Step ST7 and a portion of the control circuit 728 for carrying out
this step cooperate with each other to serve as means for
sequentially selecting an odd number of successive pulse amplitudes
R.sub.i-2, R.sub.i-1, R.sub.i, R.sub.i+1, R.sub.i+2 from the series
of determined pulse amplitudes R. Step ST8 and a portion of the
control circuit 728 for carrying out this step cooperate with each
other to serve as means for replacing the middle or center pulse
amplitude R.sub.i with the pulse amplitude R.sub.j which has a
median amplitude of the selected odd number of pulse amplitudes.
Steps ST3, ST5, ST6, ST7, and ST8 and a portion of the control
circuit 728 for carrying out these steps cooperate with each other
to serve as means for smoothening the series of determined pulse
amplitudes R. However, other kinds of smoothening means may be
employed.
For example, Steps ST3, ST5, and ST6 may be omitted from the flow
chart of FIG. 52, or Steps ST7 and ST8 may be omitted from the
same. Alternatively, Step ST8 may be replaced with a step where the
middle pulse amplitude R.sub.i is replaced with an average of the
selected odd number of pulse amplitudes R.sub.i-2, R.sub.i-1,
R.sub.i, R.sub.i+1, R.sub.i+2. Only if a smoothing technique in any
sense is applied to a series of determined pulse amplitudes R in
determining a BP value of a living subject, the BP apparatus 700
outputs the first series of determined pulse amplitudes R and the
second series of smoothened pulse amplitudes S, such that one
series of the first and second series of pulse amplitudes R, S are
superimposed on the other series in a common two-dimensional graph.
In addition, the BP apparatus 700 outputs, based on a determined
correction degree C, a degree of propriety of the measurement
conditions under which the BP value of the subject is obtained.
Thus, in any case, medical workers can easily judge, from the
output of the BP apparatus 700, whether the measurement condition
is proper or appropriate.
In each of the graphs shown in FIGS. 53 to 57, it is possible to
exchange two symbols with each other for representing the two
series of pulse amplitudes R, S, respectively. Moreover, in place
of the vertical lines or the vertical bars, it is possible to use
other symbols, patterns, or figures such as "star" mark or "snow"
mark. In the graph of FIG. 53, the areas A may not be blacked out
and only the polygonal line, vertical lines, and envelope of the
vertical lines may be presented. In the graph of FIG. 54, the areas
A may be blacked out. In each graph, the areas A may otherwise be
made distinct by, e.g., being hatched with, e.g., oblique lines or
a checked pattern.
Although in each of the graphs shown in FIGS. 53 and 55 the areas A
are blacked out in the same manner irrespective of whether the
determined pulse amplitudes R are higher or lower than the
corresponding smoothened pulse amplitudes S, it is possible to
distinguish some of the areas A where the determined pulse
amplitudes R are higher than the corresponding smoothened pulse
amplitudes S, from the other of the areas A where vice versa, by
using different hatchings such as different oblique-line
patterns.
From the output 742 of the BP apparatus 700 shown in FIG. 53, it is
possible omit either one of (a) the pulse-amplitude indication area
744 where the two series of pulse amplitudes R, S are output, and
(b) the measurement-condition indication area 746 where the
correction degree C is output. From either one of the two sorts of
information 744, 746 provided by the apparatus 700, medical workers
can easily judge whether the measured BP values of the living
subject contain excessively large errors due to external factors,
i.e., whether the measurement condition is proper. In the case
where the correction degree C is not determined or output, Steps
S308 to S310 of the flow chart of FIG. 51 are omitted.
Although in the sixth embodiment the correction degree C is
determined based on a ratio of the sum SD to the sum SS of the
smoothened pulse amplitudes S, it is possible to calculate a
different correction degree, C', based on a ratio of the sum SD to
a sum, SR, of the determined pulse amplitudes R. Otherwise, it is
possible to calculate a different correction degree by exchanging,
in each of the two ratios, the numerator and the denominator with
each other. In the cases where the ratios other than the ratio
SD/SS are used, different criteria and/or reference values may be
employed for judging whether the measurement condition is
proper.
While in the sixth embodiment the correction degree C is calculated
from the determined and smoothened pulse amplitudes R, S which
correspond to a prescribed range of cuff pressure values P.sub.c,
it is possible to employ a different cuff-pressure range, as
needed. For example, all the first and second series of pulse
amplitudes R, S that correspond to all the cuff pressure values
P.sub.c may be used to determine the correction degree C.
Otherwise, a first narrow cuff-pressure range whose center value
corresponds to the systolic BP value of the subject and a second
narrow cuff-pressure range whose center value corresponds to the
diastolic BP value of the same may be employed for the same purpose
in these cases, too, different criteria and/or reference values may
be employed for judging whether the measurement condition is
proper.
Although in the sixth embodiment the output device 738 provides the
recording sheet 742 bearing one or both of the pulse-amplitude
indication 744 and the measurement-condition indication 746, it is
possible to modify the output device 738 such that the output
device 738 displays, on the image display panel thereof, one or
both of the two indications 744, 746.
It is to be understood that the present invention may be embodied
with other changes, improvements, and modifications that may occur
to those skilled in the art without departing from the scope and
spirit of the present invention defined by the appended claims.
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